I have been studying Luke 1 and the message of God to Mary through the angel Gabriel about the son she was to bear. If the language of verse 31 did not make it clear, as Isaiah 7:14 should have been called to her mind, Gabriel went on to clarify in verses 32 and 33. (Scriptures quoted from ESV, using https://www.biblegateway.com.)
Luke 1:31 And behold, you will conceive in your womb and bear a son, and you shall call his name Jesus. 32 He will be great and will be called the Son of the Most High. And the Lord God will give to him the throne of his father David, 33 and he will reign over the house of Jacob forever, and of his kingdom there will be no end.”
The very name "Jesus" is the Greek equivalent of Joshua or Yeshua, names that are associated with a word group in Hebrew that pertains to salvation and deliverance. It can be rendered 'He will save.' The Hebrew understanding of deliverance required the belief that all deliverance comes from God Himself, whether a human agent is used or not. (learned at http://blueletterbible.com using Strong's (H3442, root H3091); http://abarim-publications.com regarding the word group, which quotes HAW Theological Workbook of the Old Testament regarding "savior" and deliverance. Also read the article, The Rabbi, the Note and the Messiah in the May 30, 2013 issue at http://israeltoday.co.il)
This man, this descendant who would one day occupy David's throne and "uphold it with justice and righteousness" (Isaiah 9:7) was also to be known as Immanuel 'God with us' (Isaiah 7:14). It is not simply an indication that God is on the side of Israel, but rather present with them. God's desire was always to dwell with His people, but sin was the barrier.
In Isaiah 9:6, we see that He is not only designated Son of the Most High, but also, this child born unto them, the son given unto them would be "called Wonderful Counselor, Mighty God, Everlasting Father, Prince of Peace." I see both Almighty and the trinity in these titles.
Wonderful Counselor is the Holy Spirit. The Spirit of Christ and the Holy Spirit are One in the same Spirit.
Mighty God is certainly the Almighty. He is King of the Universe.
Everlasting Father is self-evident, but I see this as both an indication of His role as Creator and also of His position as Head of the household of God, full of love for His people. ("In the beginning was the Word...and the Word was God" John 1:1) and Colossians 1:15
"He is the image of the invisible God, the firstborn of all creation. 16 For by[f] him all things were created, in heaven and on earth, visible and invisible, whether thrones or dominions or rulers or authorities—all things were created through him and for him. 17 And he is before all things, and in him all things hold together. 18 And he is the head of the body, the church. He is the beginning, the firstborn from the dead, that in everything he might be preeminent. 19 For in him all the fullness of God was pleased to dwell, 20 and through him to reconcile to himself all things, whether on earth or in heaven, making peace by the blood of his cross.")
Finally, Prince of Peace indicates the One who brings peace as a son who reconciles his brothers and sisters--both Israel and all believing humanity--to the Father (As in 2 Corinthians 5:19).
Jesus needed to ascend for His Spirit, the Holy Spirit, another Counselor, to come indwell His followers.
John 16:7 Nevertheless, I tell you the truth: it is to your advantage that I go away, for if I do not go away, the Helper will not come to you. But if I go, I will send him to you. 8 And when he comes, he will convict the world concerning sin and righteousness and judgment:
Other translations use "Counselor" where the ESV has "Helper." This is clearly the Spirit, and one with the Father and with Jesus, as indicated in the verses that follow in John 16:
12 “I still have many things to say to you, but you cannot bear them now. 13 When the Spirit of truth comes, he will guide you into all the truth, for he will not speak on his own authority, but whatever he hears he will speak, and he will declare to you the things that are to come. 14 He will glorify me, for he will take what is mine and declare it to you. 15 All that the Father has is mine; therefore I said that he will take what is mine and declare it to you."
John the Baptist, like prophets of old, was filled with the Holy Spirit. Luke 1 said he would be filled from birth.
Luke 1:15 "for he will be great before the Lord. And he must not drink wine or strong drink, and he will be filled with the Holy Spirit, even from his mother's womb. 16 And he will turn many of the children of Israel to the Lord their God, 17 and he will go before him in the spirit and power of Elijah, to turn the hearts of the fathers to the children, and the disobedient to the wisdom of the just, to make ready for the Lord a people prepared.”
Notice in the verses above that John would "make ready for the Lord a people prepared." John was preparing the people for the visitation of the Lord Himself. The act of God by His Holy Spirit that conceived the baby in Mary's womb was also by the Holy Spirit.
He, the Spirit, is not confined, but while Jesus was walking the earth, fulfilling His ministry, the role of the Holy Spirit among people was being fulfilled through Him. Jesus, Son of David, was conceived in Mary's womb as an act of God, implanting HIMSELF as the human agent of salvation to enter the world.
Jesus has fulfilled the role of Prince of Peace.
John 14:27 Peace I leave with you; my peace I give to you. Not as the world gives do I give to you. Let not your hearts be troubled, neither let them be afraid.
He who said, "I and the Father are one" (John 10:30) has become our Wonderful Counselor. It is His Spirit in us that brings God's Word to life and shines it in our hearts and lives.
John 14:16 "And I will ask the Father, and he will give you another Helper,[f] to be with you forever, 17 even the Spirit of truth, whom the world cannot receive, because it neither sees him nor knows him. You know him, for he dwells with you and will be[g] in you.
18 “I will not leave you as orphans; I will come to you. 19 Yet a little while and the world will see me no more, but you will see me. Because I live, you also will live. 20 In that day you will know that I am in my Father, and you in me, and I in you."
To those who trust Him, He is Mighty God--He is the King of our hearts, ruling and reigning over our sinful desires, because we know He is King of kings and Lord of lords.
Jesus gives us access to the heavenly throne room by His work of reconciliation, that we may experience God as our loving Everlasting Father, rather than as our Judge and executioner. One day He will rule and reign over every human being on the face of the earth.
Philippians 2:10 "so that at the name of Jesus every knee should bow, in heaven and on earth and under the earth,"
God Himself, Who was rejected as king by the house of Jacob ( and 1 Samuel 8:7) will be restored to the throne in Israel (Luke 1:33) --also for 'not Israel' the Gentiles, but that is another discussion. Not that God ever abdicated His heavenly throne, but practically speaking, He will be recognized as King by all, having humbled Himself in the form of a servant, yet without relinquishing His deity, as discussed by others in this post.
Isaiah 9:10 states, "In that day the root of Jesse, who shall stand as a signal for the peoples--of him shall the nations inquire, and his resting place shall be glorious."
Jesse was the father of David. To be the root of Jesse, Jesus has to precede him. Yet, Jesus is born later. This is the great mystery. This is what makes Jesus so special and different from any human being born before or since. "Before Abraham was, I am" was His claim:
John 8:56 "Your father Abraham rejoiced that he would see my day. He saw it and was glad.” 57 So the Jews said to him, “You are not yet fifty years old, and have you seen Abraham?”[d] 58 Jesus said to them, “Truly, truly, I say to you, before Abraham was, I am.” 59 So they picked up stones to throw at him, but Jesus hid himself and went out of the temple.
The Jewish religious leaders clearly understood Jesus' claim to be Almighty--otherwise, they would have had no cause or thought to stone him for what they saw as blasphemy.
He had argued against their accusations of blasphemy for claiming to be Son of God. No Jew went around calling God "Father," but this was much deeper than how Jesus chose to address the Almighty in His prayers. It had more to do with what He thought of Himself, what identity He portrayed with His words:
John 10:33 The Jews answered him, “It is not for a good work that we are going to stone you but for blasphemy, because you, being a man, make yourself God.” 34 Jesus answered them, “Is it not written in your Law, ‘I said, you are gods’? 35 If he called them gods to whom the word of God came—and Scripture cannot be broken— 36 do you say of him whom the Father consecrated and sent into the world, ‘You are blaspheming,’ because I said, ‘I am the Son of God’? 37 If I am not doing the works of my Father, then do not believe me; 38 but if I do them, even though you do not believe me, believe the works, that you may know and understand that the Father is in me and I am in the Father.” 39 Again they sought to arrest him, but he escaped from their hands.
This was right after Jesus stated that He is the good shepherd, who lays down His life for the sheep, who grants eternal life to those who hear His voice, and that He and the Father are one.
In conclusion, look at this perspective from Peter on the Old Testament prophets in regard to the Holy Spirit:
1 Peter 1:10 "Concerning this salvation, the prophets who prophesied about the grace that was to be yours searched and inquired carefully, 11 inquiring what person or time[a] the Spirit of Christ in them was indicating when he predicted the sufferings of Christ and the subsequent glories. 12 It was revealed to them that they were serving not themselves but you, in the things that have now been announced to you through those who preached the good news to you by the Holy Spirit sent from heaven, things into which angels long to look."
I hope this helps magnify Jesus in your eyes and pray it makes clear the connections in the Scriptures that support the trinitarian view that Jesus is the Almighty.
...I struggle to understand the doctrine of the Trinity" So do Trinitarians.