The word/term "trinity" is never used in the Bible. However, most Christians believe that God exists as three persons in one God-head.
This question has two parts:
While the word Trinity does not occur in scripture, the concept and idea of the Trinity does, if you have eyes to see and ears to hear. A detailed treatment of the Trinity with linked references can be found on GodAndScience.org.
In the following scriptural quotes, all bold text is my emphasis (in fact, there is no use of italics or bold in scripture), and note I tend to link to the whole chapter so it's easy to see the verses in context).
Fair warning: This going to be long, and even so it is only scratching the surface of an understanding that typically seems to take decades for most Christians to grow into in their understanding of God. The TL;DR answer begins with the heading for "God is Trinity"
Let's examine the scriptures to speak to God's plurality, and then see if we can understand the way that one God can also be three.
The first hint you can see is in Genesis 1, at the end of Day 6 when God creates man:
Gen 1:26-27
26 Then God said, “Let us make mankind in our image, in our likeness, so that they may rule over the fish in the sea and the birds in the sky, over the livestock and all the wild animals, and over all the creatures that move along the ground.”
27 So God created mankind in his own image, in the image of God he created them; male and female he created them.
From this passage we could deduce that in some way, God is in some manner plural. (We can also see that the image of God is both male and female, even though scripture consistently refers to the Godhead in the male gender).
Actually, though it's not obvious from the English, the first indication of plurality in God is in the very first verse in the Hebrew word for God:
The Hebrew word translated "God" is the word El or Elohim. Elohim is the plural form of El. The plural form is used 2607 of the 2845 times the word "God" is used in the Old Testament. Not only is the word for God usually used in the plural form, but several verses refer to God as "Us"
An example of how the Hebrew word Elohim is used in the plural is that it is translated "gods" (referring to idols) 235 times in the Old Testament. It is exactly the same word that is translated "God," referring to the Almighty. An example is given below:
"I am the LORD your God [Elohim], who brought you out of the land of Egypt, out of the house of slavery. "You shall have no other gods [Elohim] before Me. (Exodus 20:2-3)
There are a huge number of verses in scripture that ascribe the same divine attributes to both the Father and the Son. But to me, more "obvious" are the scriptures which state Jesus is God, outright.
22 All this took place to fulfill what the Lord had said through the prophet: 23 “The virgin will conceive and give birth to a son, and they will call him Immanuel” (which means “God with us”).
John 1 speaks not only to Jesus (the Word) being God, but that all that was created was created through him (Jesus).
John 1
1 In the beginning was the Word, and the Word was with God, and the Word was God. 2 He was with God in the beginning. 3 Through him all things were made; without him nothing was made that has been made. 4 In him was life, and that life was the light of all mankind. 5 The light shines in the darkness, and the darkness has not overcome it.
...
14 The Word became flesh and made his dwelling among us. We have seen his glory, the glory of the one and only Son, who came from the Father, full of grace and truth.
15 (John testified concerning him. He cried out, saying, “This is the one I spoke about when I said, ‘He who comes after me has surpassed me because he was before me.’”) 16 Out of his fullness we have all received grace in place of grace already given. 17 For the law was given through Moses; grace and truth came through Jesus Christ. 18 No one has ever seen God, but the one and only Son, who is himself God and is in closest relationship with the Father, has made him known.
And the letter to the Colossians gives us to know that Jesus is fully God, speaking of the risen Lord (notice the present tense):
9 For in Christ all the fullness of the Deity lives in bodily form
Many more scriptures that speak to the deity of Jesus can be found here.
Jesus speaks of the Holy Spirit as a person, on equal footing with himself and his Father:
25 “All this I have spoken while still with you. 26 But the Advocate, the Holy Spirit, whom the Father will send in my name, will teach you all things and will remind you of everything I have said to you. 27 Peace I leave with you; my peace I give you. I do not give to you as the world gives. Do not let your hearts be troubled and do not be afraid.
(by the way, in case you have ever wondered, this "remind[ing] you of everything I have said to you" is how the disciples recalled and recorded the Gospels so accurately and in such detail; it was through the Holy Spirit.)
And again, in the following chapters:
26 “When the Advocate comes, whom I will send to you from the Father—the Spirit of truth who goes out from the Father—he will testify about me. 27 And you also must testify, for you have been with me from the beginning.
12 “I have much more to say to you, more than you can now bear. 13 But when he, the Spirit of truth, comes, he will guide you into all the truth. He will not speak on his own; he will speak only what he hears, and he will tell you what is yet to come. 14 He will glorify me because it is from me that he will receive what he will make known to you. 15 All that belongs to the Father is mine. That is why I said the Spirit will receive from me what he will make known to you.”
For a fuller treatment of the Holy Spirit's deity and person, see here.
So, having now seen that there are three persons in this God we serve, why do Christians then claim that there is but one God? Again, it's because this is what God has revealed in the scriptures:
Deut 6:4-5
4 Hear, O Israel: The LORD our God, the LORD is one. 5 Love the LORD your God with all your heart and with all your soul and with all your strength.
This verse from Deuteronomy is especially interesting because the same plural-form word for God is used: Yahweh Elohim, followed immediately by the declaration that he is one.
In the New Testament, we read:
4 So then, about eating food sacrificed to idols: We know that “An idol is nothing at all in the world” and that “There is no God but one.
Again, more references can be found here.
Although the word "trinity" is not used, scripture does seem to teach three distinct persons who are identified as God, such as:
18 And Jesus came and said to them, “All authority in heaven and on earth has been given to me. 19 Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, 20 teaching them to observe all that I have commanded you.
So, scripture teaches us that God is both one, and at the same time three. How can this be? First you must accept that finite man cannot fully comprehend the nature and being of an infinite God. The Trinity is a mystery - we can wrestle with it, we can approach it, we can apprehend it in our hearts, but ultimately our mind ends up only loosely understanding, like trying to wrap your mind around the concept of infinity.
Of particular concern is trying to explain God by use of analogy, these always break down, and I have never heard one to even remotely adequate to fully picture of the Trinity as alluded to in scripture (they give us a glimpse, but taken alone the picture is nearly always of a heretical understanding).
I have struggled with the idea of the Trinity all my journey, but recently I read Frank Sheed's Theology and Sanity, which I found very helpful. He does not attempt to explain by analogy, but describes God as being one nature shared by three persons. I will end with some quotes from his book (emphasis Sheed's):
The notion is unfortunately widespread that the mystery of the Blessed Trinity is a mystery of mathematics, that is to say, of how one can equal three. The plain Christian accepts the doctrine of the Trinity; the "advanced" Christian rejects it; but too often what is being accepted by one and rejected by the other is that one equals three.
...
The short statement of the doctrine is, as we have heard it all our lives, that there are three persons in one nature. But if we attach no meaning to the word person, and no meaning to the word nature, then both the nouns have dropped out of our definition, and we are left of with the numbers three and one, and get by as best we can with these.
...
The doctrine may be set out in four statements:
In the one divine nature, there are three persons - the Father, the Son and the Holy Spirit.
The Father is not the Son, the Son is not the Holy Spirit, the Holy Spirit is not the Father: no one of the persons is the either of the others.
The Father is God, the Son is God and the Holy Spirit is God.
There are not three Gods, but one God.
...
We are not saying three persons in one person, or three natures in one nature; we are saying three persons in one nature. There is not even the appearance of an arithmetical problem. It is for us to see what person is and what nature is, and the to consider what meaning there can be in a nature totally possessed by three distinct persons.
...
Nature answers the question what we are; person answers the question who we are.
Ok, I will try my best to answer this.
Isaiah 9:6 (NIV) 6 For to us a child is born, to us a son is given, and the government will be on his shoulders. And he will be called Wonderful Counselor, Mighty God, Everlasting Father, Prince of Peace.
Matthew 1:23 (NIV) 23 “The virgin will conceive and give birth to a son, and they will call him Immanuel”[a] (which means “God with us”).
John 20:28 (NIV) 28 Thomas said to him, “My Lord and my God!” -Thomas
Titus 2:13 (NIV) 13 while we wait for the blessed hope—the appearing of the glory of our great God and Savior, Jesus Christ, -Paul
Philippians 2:6 (NIV) 6 Who, being in very nature[a] God, did not consider equality with God something to be used to his own advantage;
John 5:18 (NIV) 18 For this reason they tried all the more to kill him; not only was he breaking the Sabbath, but he was even calling God his own Father, making himself equal with God.
John 10:30 (NIV) 30 I and the Father are one.”
Genesis 1 1 In the beginning God created the heavens and the earth.
Colossians 1:15-16 (NIV) 15 The Son is the image of the invisible God, the firstborn over all creation. 16 For in him all things were created: things in heaven and on earth, visible and invisible, whether thrones or powers or rulers or authorities; all things have been created through him and for him.
2 Corinthians 3:17 (NIV) 17 Now the Lord is the Spirit, and where the Spirit of the Lord is, there is freedom.
Isaiah 45:21 (NIV) 21 Declare what is to be, present it— let them take counsel together. Who foretold this long ago, who declared it from the distant past? Was it not I, the LORD? And there is no God apart from me, a righteous God and a Savior; there is none but me.
The Father, The Son and the Holy Spirit live inside of the Children of God.
2 Corinthians 13:5 (NIV) 5 Examine yourselves to see whether you are in the faith; test yourselves. Do you not realize that Christ Jesus is in you—unless, of course, you fail the test?
John 14:23 (NIV) 23 Jesus replied, “Anyone who loves me will obey my teaching. My Father will love them, and we will come to them and make our home with them.
Ezekiel 36:26-27 (NIV) 26 I will give you a new heart and put a new spirit in you; I will remove from you your heart of stone and give you a heart of flesh. 27 And I will put my Spirit in you and move you to follow my decrees and be careful to keep my laws.
Phew... hope that helps.
However, most Christians believe that God exists as three persons in one God-head.
This may or may not be true. I think it is more true to say that nominal acquiescence of a statement of trinitarianism is widely understood as a 'red line' for acceptance by many denominations. The Nicene creed for example is clearly trinatarian, and so are many 'statements of faith' such as the one held by the church I am a member of.
Historically, this came about at least in part because of the rise of Arianism which included the concept that Christ was created by the Father and not co-eternal with Him. Similar theological frameworks have arisen ever since and many are popular today.
It suits our human nature to have easily understood lines between 'us' and 'the heretics' (or 'saved' and 'unreached'), and of course insofar as these lines reflect the true revelation of God, they can be very helpful. The controversy over the trinity is caused by the superficial lack of the term in scripture. However I'd argue that the question and much discussion about the doctrine of the trinity in general, is an example of the difficulties encountered when you try to get a cart to pull a horse rather than the other way round:
What is the Biblical basis for the doctrine of the Trinity?
A re-phrasing of this question that I'd suggest lends itself towards a seeking of a deeper understanding of the nature and revelation of God would be: "To what degree is the revelation from God in scripture about the plurality in His nature accurately summed up in the statement that God exists as three persons in one God-head?"
A question like this does not promote the idea that we must examine scripture to support our doctrines1, but rather that we should examine scripture to challenge and shape our doctrines and framework. This question presupposes a possible weakness or incompleteness in the doctrine rather than in God's revelation
By way of a practical example of why this matters, here are some questions that might provoke a defensive reaction in a person who holds fast to a doctrine instead of the Word of God, rather than holding on to a doctrine as a summary of the Word of God:
"Is the Holy Spirit a 'person' in exactly the same sense as Jesus?"
"What does the blurred line between angels and God Himself in many passages indicate about the nature and plurality of God?"
"Do the Father and Jesus each have a 'spirit' distinct from the Holy Spirit?"
"If so, Does the Holy Spirit have a 'spirit' (small 's') too?"
"If 'trinity' is the best one-word summary of the revealed plurality of God in scripture, what is the best 10 word summary?"
So, what is the answer to the alternative question I posed:
To what degree is the revelation from God in scripture about the plurality in His nature accurately summed up in the statement that God exists as three persons in one God-head?
I'll sum up my own thinking here and attempt to give some scriptural support. A full answer is impossible, because the question by design encourages us ever deeper into the richness of God's word.
The traditional understanding of 'distinct person' but 'same substance' (homooúsios) has value, but is rather abstract. I prefer to ask the question 'in what ways is God three and in what ways is God one' in the light of texts like these:
30I and the Father are one.” John 10, ESV
Here the sense is 'alignment'. We cannot be allied to the Father and opposed to the son or vice versa. The Father's sheep and the Son's sheep are the same group.
9Jesus said to him, “Have I been with you so long, and you still do not know me, Philip? Whoever has seen me has seen the Father. How can you say, ‘Show us the Father’? 10Do you not believe that I am in the Father and the Father is in me? The words that I say to you I do not speak on my own authority, but the Father who dwells in me does his works. John 14, ESV
Here the sense seems to include 'faithfulness'. The Father and Son are united in the sureness of their words and in their character and works.2
In this case and the previous, the distinct personhood of Jesus and the Father are obvious and not denied. Jesus does not say "I am the Father" meant in the sense of modalism or otherwise, but emphasizes a particular aspect or aspects of unity.
26But the Helper, the Holy Spirit, whom the Father will send in my name, he will teach you all things and bring to your remembrance all that I have said to you. John 14, ESV
Here the unity between the Spirit and the Son is a unity of purpose: the mission is shared and so is the message.
33And he took with him Peter and James and John, and began to be greatly distressed and troubled. 34And he said to them, “My soul is very sorrowful, even to death. Remain here and watch.” 35And going a little farther, he fell on the ground and prayed that, if it were possible, the hour might pass from him. 36And he said, “Abba, Father, all things are possible for you. Remove this cup from me. Yet not what I will, but what you will.” Mark 14, ESV
This extraordinary and fascinating passage at first look implies that the 'will' of the Father and the Son are part of their distinct 'personhood' rather than part of their united 'substance'. However it is more naturally understood as a conflict within the united will of God rather than between the divine persons: Both Jesus and the Father in some sense want the cup removed from Jesus, and both Jesus and the Father's ultimate desire is for the Father's ultimate will to be done. There is much more that could be said here.
There are passages in the Bible that speak of the plurality of God without being obviously (in a non-contrived way) trinitarian. In these cases I see no need to force the doctrine of the trinity into these passages; that would be to elevate the doctrine above scripture:
18:1And the Lord appeared to him by the oaks of Mamre, as he sat at the door of his tent in the heat of the day. 2He lifted up his eyes and looked, and behold, three men were standing in front of him. [...] 22So the men turned from there and went toward Sodom, but Abraham still stood before the Lord. [...] 19:1The two angels came to Sodom in the evening... Genesis 18 and 19, ESV
2And the angel of the Lord appeared to him in a flame of fire out of the midst of a bush. He looked, and behold, the bush was burning, yet it was not consumed. 3And Moses said, “I will turn aside to see this great sight, why the bush is not burned.” 4When the Lord saw that he turned aside to see, God called to him out of the bush, “Moses, Moses!” And he said, “Here I am.” Exodus 3, ESV
14And he said, “No; but I am the commander of the army of the Lord. Now I have come.” And Joshua fell on his face to the earth and worshiped and said to him, “What does my lord say to his servant?” 15And the commander of the Lord's army said to Joshua, “Take off your sandals from your feet, for the place where you are standing is holy.” And Joshua did so. Joshua 5, ESV
To my mind all three of these passages hint at the unity between God and His angels: the sense is that they are in a way like an appendage or an extension of His right arm rather than distinct 'beings'. Yet in another sense and in many other passages it is clear that they are distinct too. This is a similar conceptually to the trinity, but it does not seem to me to be the same thing.
In summary: 'trinity' or 'three persons in one God-head' is a useful and accurate doctrine statement. It is also basic and incomplete. God's word is deeper and broader than any doctrine, revealing the secret and hidden wisdom of God, and it is there we most usefully expend our effort.
1 in the broad sense of the word
2 there is a fascinating theme of unity not just within the Godhead but between God and man in John 14 which is part of a wider 'whole Bible' theme
To answer your second question, there is Acts 7:55-56 in which Stephen, being full of the Holy Ghost, looks up and sees God the Father and Christ on His right hand. This passage shows all three personages together, although perhaps not in the way you are looking for (since it seems to suggest that they are three personages are distinct beings).
Obviously Stephen felt the Holy Ghost or its influence, which may or may not be interpreted as the literal presence. And while Stephen saw God and Christ, we can only speculate as to whether their literal presence was there or if it was simply a vision. Regardless, the scripture "shows" all three persons in a way that was very real to Stephen the apostle.
To add to the litany of proof-texts, may I suggest the baptism of Jesus in the Jordan (whereupon the Holy Spirit descended and lit on His shoulder, and God the Father spoke out of the heavens in affirmation of His Son) in Matthew 3:16-17, Mark 1:9-11, and Luke 3:21-22, and His transfiguration in Matthew 17:5 and Mark 9:7.
Also, our Lord's command to baptize all nations was to "baptize in the name of the Father, and of the Son, and of the Holy Spirit." Matthew 28:19.
The formulation of the doctrine of the Trinity took seven councils to reach what we have today, but it plainly is not foreign to the Gospels.
For more than 3,000 years, Jews have repeated Deuteronomy 6:4. “Hear, O Israel: The Lord our God is one Lord.” This sacred passage has been held in high esteem and memorized by Jews for centuries.
Jesus also taught about “the only true God”
John 17:3 And this is life eternal, that they might know thee the only true God, and Jesus Christ, whom thou hast sent.
The Oneness doctrine, however, overlooks the fact that the Son came to earth to reveal the true character of God the Father to a world groping in spiritual blindness.
Trinity is woven in scriptures:
On birth of Jesus Christ and His life, Death and Resurrection, it became increasingly self evident from the Bible itself the existence of Trinity or Triune God. Most obvious and direct evidence for Trinity emanated from Bible, depicting Jesus Christ and Holy Spirit with Nature of God. Therefore, to quote from the Athanasian Creed:
So the Father is God, the Son is God, the Holy Spirit is God; And yet there are not three Gods, but one God.”
If Father is God, Son is God and Holy Spirit is God than that’s it. There are numerous verses in Bible to vie for the Divinity of these three Persons in one God and that is how this answer has become such a long post.
Bible gives us irrefutable references about these claims. It never became that clear until the Son was revealed in NT. Second person was revealed by arrival of Jesus and the third person was revealed after Jesus was glorified. That’s how we find most of the references to God the father in OT, God the Son in Gospels and majority of the references in explaining God the Holy Spirit, after Jesus was glorified.
Jesus is same as God:
When Jesus prayed to His Father in Gethsemane, He said:
John 17:5-6 “And now, O Father, glorify thou me with thine own self with the glory which I had with thee before the world was. I have manifested thy name unto the men which thou gavest me out of the world”
Jesus is the only one who could reveal the Father, because He is the express image of the Father (Luke 10:22; Thus when the disciples asked Christ what the Father was like, He could say:
John 14:9 Jesus replied, “Have I been with you for so long, and you have not known me, Philip? The person who has seen me has seen the Father! How can you say, ‘Show us the Father’?
Jesus so mirrored the character of the Father that He perfectly reflected Him, hence the title “The Everlasting Father”(Isaiah 9:6). I Another reason Jesus is called the Everlasting Father is because this world and everything in it was created through Christ. So in a very real sense, Jesus is our father:
Hebrews 1:2 in these last days he has spoken to us in a son, whom he appointed heir of all things, and through whom he created the world.
In Isaiah 9:6 Jesus is called the Father and here Old Testament refers Jesus to be same as Father.
Isaiah 9:6 For a child has been born to us, a son has been given to us. He shoulders responsibility and is called: Extraordinary Strategist, Mighty God, Everlasting Father, Prince of Peace.
Jesus also calls Himself the Son of man, our brother, our shepherd, our friend, and our priest. Jesus frequently said many things that left a clear impression about His "human" nature. Nonetheless, at many other places in Bible, Jesus makes us abundantly clear about His "Divine" nature as well. This was however an indispensable necessity for the promised Messiah-to be both human and Divine- as otherwise His death on cross would have no power to provide salvation for humankind.
Philippians 2:5-8 “Let this mind be in you, which was also in Christ Jesus: Who, being in the form of God, thought it not robbery to be equal with God: But made himself of no reputation, and took upon him the form of a servant, and was made in the likeness of men: And being found in fashion as a man, he humbled himself, and became obedient unto death, even the death of the cross”
As we compare Scripture definitions for God with the Bible record of Jesus, we see the characteristics of Jehovah are also ascribed to Jesus.
He is self-existent (John 1:1–4; 14:6); only God is self-existent (Psalm 90:2).
Jesus defines Himself as eternal. “I am Alpha and Omega, the beginning and the ending, saith the Lord, which is, and which was, and which is to come, the Almighty” (Revelation 1:8).
He is, and has, eternal life (1 John 5:11, 12, 20).
He is all-powerful (Revelation 1:8).
He created all things (John 1:3). “In the beginning God created the heaven and the earth” (Genesis 1:1). “For by Him all things were created that are in heaven and that are on earth, visible and invisible, whether thrones or dominions or principalities or powers. All things were created through Him and for Him” (Colossians 1:16 NKJV).
The Father even calls Jesus God. “But unto the Son he saith, Thy throne, O God, is for ever and ever: a scepter of righteousness is the scepter of thy kingdom”
Hebrews 1:8-9. but of the Son he says, “Your throne, O God, is forever and ever, and a righteous scepter is the scepter of your kingdom. 1:9 You have loved righteousness and hated lawlessness. So God, your God, has anointed you over your companions with the oil of rejoicing.”
Jesus is able to forgive sin (Luke 5:20, 21); The Bible says only God can forgive sin (Isaiah 43:25).
Jesus accepted worship that according to the Ten Commandments is reserved only for the Almighty.
Matthew 14:33 Then they that were in the ship came and worshipped him, saying, Of a truth thou art the Son of God.
Matthew 28:9“And as they went to tell his disciples, behold, Jesus met them, saying, ‘All hail.’ And they came and held him by the feet, and worshipped him”
John 20:26–29 Upon seeing the risen Savior, the converted skeptic, Thomas, confessed, “My Lord and my God!”
Even the angels worship Jesus. “And again, when he bringeth in the first begotten into the world, he saith, And let all the angels of God worship him” (Hebrews 1:6).
The Scriptures also teach that only God knows the thoughts of a man’s heart (1 Kings 8:39). Yet Jesus consistently knew what people were thinking, “for he knew what was in man” (John 2:25). “Nathanael said to Him, ‘How do You know me?’ Jesus answered and said to him, ‘Before Philip called you, when you were under the fig tree, I saw you’” (John 1:48 NKJV).
Through the Spirit, Jesus is omnipresent. “Lo, I am with you always, even to the end of the age” (Matthew 28:20 NKJV). “For I am with you, and no one will attack you to hurt you; for I have many people in this city” (Acts 18:10 NKJV).
He has power to give life, and even resurrected Himself. “No man taketh it from me, but I lay it down of myself. I have power to lay it down, and I have power to take it again” (John 10:18). “I am the resurrection, and the life: he that believeth in me, though he were dead, yet shall he live” (John 11:25).
John 10:30, 33“I and my Father are one,” Jewish leaders were outraged and sought to execute Him. They understood unequivocally that Jesus was claiming to be God Himself. “The Jews answered him, saying, For a good work we stone thee not; but for blasphemy; and because that thou, being a man, makest thyself God”.
John 8:58 NKJV Jesus said to them, “‘Most assuredly, I say to you, before Abraham was, I AM.’ Then they took up stones to throw at Him; but Jesus hid Himself and went out of the temple, going through the midst of them, and so passed by”.
John 5:17, 18 “‘My Father worketh hitherto, and I work.’ Therefore the Jews sought the more to kill him, ... but said also that God was his Father, making Himself equal with God”.
Therefore, by considering the primary definitions of God, and seeing that Jesus fits every one of those definitions, obviously, Jesus must be eternal God.
References to Trinity in Bible
The Old Testament was written long before the existence of the Christian church, apostate or true, and it teaches there are three persons in the Godhead in Isaiah:
Isaiah 48:16, 17 Come ye near unto me, hear ye this; I have not spoken in secret from the beginning; From the time that it was, there am I: And now the Lord God, and his Spirit, hath sent me.
“I was watching in the night visions, And behold, One like the Son of Man, Coming with the clouds of heaven! He came to the Ancient of Days, And they brought Him near before Him” (Daniel 7:13).
The Son of man, Jesus, is seen coming before the Ancient of Days—who is, obviously, God the Father.
Paul frequently referred to the three separate persons of the Godhead.
“The grace of the Lord Jesus Christ, and the love of God, and the communion of the Holy Ghost, be with you all” (2 Corinthians 13:14).
“How much more shall the blood of Christ, who through the eternal Spirit offered himself without spot to God, purge your conscience from dead works to serve the living God?” (Hebrews 9:14).
We clearly see three distinct persons at the baptism of Jesus.
“And Jesus, when he was baptized, went up straightway out of the water: and, lo, the heavens were opened unto him, and he saw the Spirit of God descending like a dove, and lighting upon him: And lo a voice from heaven, saying, This is my beloved Son, in whom I am well pleased” (Matthew 3:16, 17).
Here God the Father bears witness to God the Son through God the Holy Spirit in the form of a dove. And on top of this, it is through the shared authority of these three persons that we are commissioned to baptize.
“Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost” (Matthew 28:19).
In John 16:12-15, Jesus gives in His own words gives a glimpse of the Trinity:
"I have much more to tell you, but now it would be too much for you to bear. When however the Spirit comes who reveals the truth about God he will lead you into all truth. He will not speak on his own authority, but he will speak of what he hears and will tell you of things to come. He will give me glory, because he will take what I say and tell it to you. All that my Father has is mine; that is why I said that the Spirit will take what I give him and tell it to you."
Paul gives us the idea of Trinity in this verse:
Romans 15:30 . Now I beseech you, brethren, for the Lord Jesus Christ's sake, and for the love of the Spirit, that ye strive together with me in [your] prayers to God for me;
Godhead of Holy Spirit as Jesus explained here:
Matt 12:32 Whoever speaks a word against the Son of Man will be forgiven. But whoever speaks against the Holy Spirit will not be forgiven, either in this age or in the age to come.
How they are different yet One?
Again to quote from the Athanasian Creed:
Just as we are compelled by the Christian truth to acknowledge each distinct person as God and Lord, so also are we prohibited by the catholic religion to say that there are three Gods or Lords.
The Father is not made nor created nor begotten by anyone.
The Son is neither made nor created, but begotten of the Father alone.
The Holy Spirit is of the Father and of the Son, neither made nor created nor begotten, but proceeding.
Thus, there is one Father, not three Fathers; one Son, not three Sons; one Holy Spirit, not three Holy Spirits.
And in this Trinity none is before after another; none is greater or less than another;
But the whole three persons are coeternal with each other and coequal, so that in all things, as has been stated above, the Trinity in Unity and Unity in Trinity is to be worshiped.
It would be pompous and preposterous to pretend that we understand everything about God.
“O the depth of the riches both of the wisdom and knowledge of God! how unsearchable are his judgments, and his ways past finding out!” (Romans 11:33).
If we could completely unpack Him like cracking some genetic code, He would cease to be God. John Wesley said, “Bring me a worm that can comprehend a man, and then I will show you a man that can comprehend the triune God!”
Nevertheless, there is much about God that is revealed for our blessing.
“The secret things belong unto the Lord our God: but those things which are revealed belong unto us and to our children for ever” (Deuteronomy 29:29).
What is revealed is that this teaching of the trinity must be important to God. The ministry of Jesus both begins and ends with an emphasis on the three persons in the Godhead. The Father, Son, and Spirit are present at Jesus’ baptism and when He ascends to heaven. Jesus commanded His followers to baptize in the name of Father, Son, and Holy Spirit.
The testimony of Scripture indicates that the Godhead can neither be separated into three Gods nor merged into one person.
This answer deliberately excludes Christian writings of the Pre-Nicene and Nicene church writers and leaders (A.D. c. 90-c. 325) so as to explain the Trinity doctrine solely in light of the inspired Greek NT Scriptures (A.D. c. 50-c. 90).
God is not one person (Unity) but three persons (Trinity).
Monotheism is not the same as Unitarianism. The former tells us that God is one while the latter tells us that God is one person.
Only God is the one Lord (Deuteronomy 6:4) and only God possesses divine nature (John 17:3 cf. Galatians 4:8).In these terms, no creature is exactly like God (Isaiah 40:18). God's oneness is his uniqueness (source).
The phrase 'God the Father' is scriptural.
From Paul, an apostle who is not sent from human authority or commissioned through human agency, but sent through Jesus Christ and God the Father who raised him from the dead; (Galatians 1:1 CEB)
To the Father is ascribed primarily but not solely the appellation theos (God).
God the Father possesses one hupostasis (nature). The divinity of the Father is his own glory, the invisible attributes and divine nature (Greek: theiotes - Rom 1:20-25) which cannot be shared to idols (Isaiah 42:8).
The phrase 'God the only Son' (monogenes theos) is found in John 1:18.It is a variant of the phrase 'God the Son' which became a common designation for the second person of the Trinity.
No one has ever seen God. God the only Son, who is at the Father’s side, has made God known (John 1:18 CEB)
Jesus is called theos (God) in the strictest sense of the word.
Jesus is God himself in the flesh (Colossians 2:9).
Jesus is called God because he shares in the divine identity of the one God (source).
Jesus receives latreutic worship (Daniel 7:14 LXX;Revelation 5:13,14:4, 22:3) and receives prayers (John 14:14 cf. 1 Corinthians 16:22).
Note that any biblical passage that speaks of Christ as "inferior" to the Father is a mere reference to his being "the only Son", having begotten from God from all eternity (Ps. 110:3 LXX; John 1:1,18 cf. 3:16) as well as to his being "fully human" , having become flesh (John 1:1-14 cf. Phil 2:7-8).
The Holy Spirit is equal to the Father and the Son (Matthew 28:19).
The Holy Spirit is ,not an another name for Jesus , but an another person (John 14:16) who proceeds from the Father (John 15:26).
He is invoked in major church activities (Matthew 28:19 - baptism | 2 Corinthians 13:14 - benediction).
Therefore, we have cogently proven from the Scriptures that the Holy Spirit, together with the Father and the Son, is worshiped and prayed to.
For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one.
1 John 5:7
And why not add the Apostle Thomas' own confession in John 20:28? "And Thomas answered and said unto him, My Lord and my God."
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Read this: Support for 1 John 5:7
My prayer is not for them alone. I pray also for those who will believe in me through their message, 21 that all of them may be one, Father, just as you are in me and I am in you. May they also be in us so that the world may believe that you have sent me. biblegateway.com/passage/?search=JOHN%2017:20-26
Commented
Mar 14, 2014 at 15:45
The New Testament not only mentions the Divine Persons of the Trinity
individually, but also frequently, more than forty times, they are mentioned together or at the same time. The main Trinitarian texts are:
Gospels:
Matt. 3:16-17 (Mark 1:10-11; Luke 3:22), the theophany at the baptism of Christ.
And Jesus being baptized, forthwith came out of the water: and lo, the heavens were opened to him: and he saw the Spirit of God descending as a dove, and coming upon him. And behold a voice from heaven [God the Father], saying: This is my beloved Son, in whom I am well pleased.Matt. 28:19, the command to baptize.
Going therefore, teach ye all nations; baptizing them in the name of the Father, and of the Son, and of the Holy Ghost.Luke 1:35, the annunciation of the Incarnation.
And the angel answering, said to her: The Holy Ghost shall come upon thee, and the power of the most High [God the Father] shall overshadow thee. And therefore also the Holy which shall be born of thee shall be called the Son of God.John 14:16, 17, 23; 15:26; 16:7-11, 12-15, the promise of the Holy Spirit at the Last Supper.
And I [God the Son] will ask the Father, and he shall give you another Paraclete [Holy Ghost], that he may abide with you for ever. The spirit of truth [Holy Ghost], whom the world cannot receive, because it seeth him not, nor knoweth him: but you shall know him; because he shall abide with you, and shall be in you. […] Jesus answered, and said to him: If any one love me, he will keep my word, and my Father will love him, and we [with the Holy Ghost] will come to him, and will make our abode with him.
[…]
But when the Paraclete [Holy Ghost] cometh, whom I [God the Son] will send you from the Father, the Spirit of truth [Holy Ghost], who proceedeth from the Father, he [Holy Ghost] shall give testimony of me.
[…]
But I [God the Son] tell you the truth: it is expedient to you that I go: for if I go not, the Paraclete [Holy Ghost] will not come to you; but if I go, I will send him to you. And when he is come, he will convict the world of sin, and of justice, and of judgment. Of sin: because they believed not in me. And of justice: because I go to the Father; and you shall see me no longer. And of judgment: because the prince of this world is already judged. I have yet many things to say to you: but you cannot bear them now. But when he, the Spirit of truth [Holy Ghost], is come, he will teach you all truth. For he shall not speak of himself; but what things soever he shall hear, he shall speak; and the things that are to come, he shall shew you. He shall glorify me; because he shall receive of mine, and shall shew it to you. All things whatsoever the Father hath, are mine. Therefore I said, that he [Holy Ghost] shall receive of mine, and shew it to you.
St. Peter:
- Acts 2:33, 38-39; 5:31-32, Peter’s first sermons.
Being exalted therefore by the right hand of God, and having received of the Father the promise of the Holy Ghost, he [God the Son] hath poured forth this which you see and hear. […] But Peter said to them: Do penance, and be baptized every one of you in the name of Jesus Christ, for the remission of your sins: and you shall receive the gift of the Holy Ghost. For the promise is to you, and to your children, and to all that are far off, whomsoever the Lord our God [the Father] shall call.
[…]
Him [God the Son] hath God exalted with his right hand, to be Prince and Saviour, to give repentance to Israel, and remission of sins. And we are witnesses of these things and the Holy Ghost, whom God hath given to all that obey him.
St. Paul:
Rom. 8:9-11, 14-17; 1 Cor. 2:10-16; Eph. 1:17; 2:17-22, the divine action in the heart of the just.
But you are not in the flesh, but in the spirit, if so be that the [Holy] Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his. And if Christ be in you, the body indeed is dead, because of sin; but the spirit liveth, because of justification. And if the Spirit of him that raised up Jesus from the dead, dwell in you; he that raised up Jesus Christ from the dead, shall quicken also your mortal bodies, because of his [Holy] Spirit that dwelleth in you. […] For whosoever are led by the [Holy] Spirit of God, they are the sons of God. For you have not received the spirit of bondage again in fear; but you have received the spirit of adoption of sons, whereby we cry: Abba (Father). For the [Holy] Spirit himself giveth testimony to our spirit, that we are the sons of God. And if sons, heirs also; heirs indeed of God, and joint heirs with Christ: yet so, if we suffer with him, that we may be also glorified with him.
[…]
But to us God hath revealed them, by this [Holy] Spirit. For the [Holy] Spirit searcheth all things, yea, the deep things of God. For what man knoweth the things of a man, but the spirit of a man that is in him? So the things also that are of God no man knoweth, but the [Holy] Spirit of God. Now we have received not the spirit of this world, but the [Holy] Spirit that is of God; that we may know the things that are given us from God. Which things also we speak, not in the learned words of human wisdom; but in the doctrine of the [Holy] Spirit, comparing spiritual things with spiritual. But the sensual man perceiveth not these things that are of the [Holy] Spirit of God; for it is foolishness to him, and he cannot understand, because it is spiritually examined. But the spiritual man judgeth all things; and he himself is judged of no man. For who hath known the mind of the Lord, that we may instruct him? But we have the mind of Christ.
[…]
That the God of our Lord Jesus Christ, the Father of glory, may give unto you the spirit of wisdom and of revelation, in the knowledge of him:
[…]
And coming, he [Jesus] preached peace to you that were afar off, and peace to them that were nigh. For by him we have access both in one [Holy] Spirit to the Father. Now therefore you are no more strangers and foreigners; but you are fellow citizens with the saints, and the domestics of God, Built upon the foundation of the apostles and prophets, Jesus Christ himself being the chief corner stone: In whom all the building, being framed together, groweth up into an holy temple in the Lord. In whom you also are built together into an habitation of God in the [Holy] Spirit.1 Cor. 6:15-20, Christians as the temple of God.
Know you not that your bodies are the members of Christ? Shall I then take the members of Christ, and make them the members of an harlot? God forbid. Or know you not, that he who is joined to a harlot, is made one body? For they shall be, saith he, two in one flesh. But he who is joined to the Lord, is one spirit. Fly fornication. Every sin that a man doth, is without the body; but he that committeth fornication, sinneth against his own body. Or know you not, that your members are the temple of the Holy Ghost, who is in you, whom you have from God; and you are not your own? For you are bought with a great price. Glorify and bear God in your body.1 Cor. 12:3-6, the distribution of charisms.
Wherefore I give you to understand, that no man, speaking by the [Holy] Spirit of God, saith Anathema to Jesus. And no man can say the Lord Jesus, but by the Holy Ghost. Now there are diversities of graces, but the same [Holy] Spirit; And there are diversities of ministries, but the same Lord; And there are diversities of operations, but the same God, who worketh all in all.2 Cor. 13:13, benediction and greeting.
The grace of our Lord Jesus Christ, and the charity of God [the Father], and the communication of the Holy Ghost be with you all. Amen.Gal. 4:4-9,14, the mission of Christ.
But when the fulness of the time was come, God sent his Son, made of a woman, made under the law: That he might redeem them who were under the law: that we might receive the adoption of sons. And because you are sons, God hath sent the [Holy] Spirit of his Son into your hearts, crying: Abba, Father. Therefore now he is not a servant, but a son. And if a son, an heir also through God. But then indeed, not knowing God, you served them, who, by nature, are not gods. But now, after that you have known God, or rather are known by God: how turn you again to the weak and needy elements, which you desire to serve again? […] You despised not, nor rejected: but received me as an angel of God, even as Christ Jesus.Eph. 3:14-19, the prayer of Paul.
For this cause I bow my knees to the Father of our Lord Jesus Christ, Of whom all paternity in heaven and earth is named, That he would grant you, according to the riches of his glory, to be strengthened by his [Holy] Spirit with might unto the inward man,That Christ may dwell by faith in your hearts; that being rooted and founded in charity, You may be able to comprehend, with all the saints, what is the breadth, and length, and height, and depth: To know also the charity of Christ, which surpasseth all knowledge, that you may be filled unto all the fulness of God.Eph. 4:4-6, the unity of the Church.
One body and one [Holy] Spirit; as you are called in one hope of your calling. One Lord, one faith, one baptism. One God and Father of all, who is above all, and through all, and in us all.Tit. 3:4-6, our regeneration.
But when the goodness and kindness of God our Saviour [Jesus] appeared: Not by the works of justice, which we have done, but according to his mercy, he saved us, by the laver of regeneration, and renovation of the Holy Ghost; Whom he hath poured forth upon us abundantly, through Jesus Christ our Saviour:Hebr. 9:14, the sacrifice of Christ.
How much more shall the blood of Christ, who by the Holy Ghost offered himself unspotted unto God, cleanse our conscience from dead works, to serve the living God?Hebr. 10:29-31, the evil of apostasy.
How much more, do you think he deserveth worse punishments, who hath trodden under foot the Son of God, and hath esteemed the blood of the testament unclean, by which he was sanctified, and hath offered an affront to the [Holy] Spirit of grace? For we know him that hath said: Vengeance belongeth to me, and I will repay. And again: The Lord shall judge his people. It is a fearful thing to fall into the hands of the living God.
St. Peter:
1 Pet. 1:1-2, greeting and benediction.
Peter, an apostle of Jesus Christ, to the strangers dispersed through Pontus, Galatia, Cappadocia, Asia, and Bithynia, elect, According to the foreknowledge of God the Father, unto the sanctification of the [Holy] Spirit, unto obedience and sprinkling of the blood of Jesus Christ: Grace unto you and peace be multiplied.1 Pet. 4:14, reproach in the name of Christ.
If you be reproached for the name of Christ, you shall be blessed: for that which is of the honour, glory, and power of God, and that which is his [Holy] Spirit, resteth upon you.
St. John:
- 1 John 4:11-16, charity.
My dearest, if God hath so loved us; we also ought to love one another. No man hath seen God at any time. If we love one another, God abideth in us, and his charity is perfected in us. In this we know that we abide in him, and he in us: because he hath given us of his [Holy] spirit. And we have seen, and do testify, that the Father hath sent his Son to be the Saviour of the world. Whosoever shall confess that Jesus is the Son of God, God abideth in him, and he in God. And we have known, and have believed the charity, which God hath to us. God is charity: and he that abideth in charity, abideth in God, and God in him.
source: Sacræ Theologiæ Summa IIA: One & Triune God p. 250
For completeness, I would also like to include the following:
Genesis 3:23 (Brenton LXX En)
23 And God said, Behold, Adam is become as one of us, to know good and evil, and now lest at any time he stretch forth his hand, and take of the tree of life and eat, and so he shall live for ever—Genesis 11:7 (Brenton LXX En)
7 Come, and having gone down let us there confound their tongue, that they may not understand each the voice of his neighbour.
Here, as in Genesis 1:1 and 1:26, the plural first person is indicated when God speaks.
Psalm 32:6 (LXX)
6 By the Word of the Lord the heavens were established; and all the host of them by the Spirit of his mouth.
(Hebrews 10:11–18 ESV)
11 And every priest stands daily at his service, offering repeatedly the same sacrifices, which can never take away sins. 12 But when Christ had offered for all time a single sacrifice for sins, he sat down at the right hand of God, 13 waiting from that time until his enemies should be made a footstool for his feet. 14 For by a single offering he has perfected for all time those who are being sanctified. 15 And the Holy Spirit also bears witness to us; for after saying, 16 "This is the covenant that I will make with them after those days, declares the Lord: I will put my laws on their hearts, and write them on their minds," 17 then he adds, "I will remember their sins and their lawless deeds no more." 18 Where there is forgiveness of these, there is no longer any offering for sin.
(Jude 20-21 ESV)
20 But you, beloved, building yourselves up in your most holy faith and praying in the Holy Spirit, 21 keep yourselves in the love of God, waiting for the mercy of our Lord Jesus Christ that leads to eternal life.
(Acts 10:38 ESV)
38 how God anointed Jesus of Nazareth with the Holy Spirit and with power.
Are there any passages that directly show all three persons of God together - and what are they?
Maybe this one ? (IMHO)
Revelation 4:3
The One seated there looked like jasper and carnelian, and a rainbow gleaming like an emerald encircled the throne.
bold is the Father.
Revelation 4:3
And out of the throne come flashes of lightning, and voices, and thunderings. And there were seven lamps of fire burning before the throne, which are the seven Spirits of God.
bold is the Holy Spirit
Revelation 5:6
Then I saw a Lamb who appeared to have been slain, standing in the center of the throne
bold is the Son.
