How does the New Testament define a brother in Christ? According to the New Testament, what makes a human a brother in Christ? And also, according to the New Testament, which people are definitely not Christians, definitely not brothers in Christ?

I would want to have a set of key critical conditions-prerequisites (elicited from the New Testament) that would be necessary conditions for a person to be considered a Christian or a brother in Christ (I mean, if a person lacks at least one of those conditions, he is definitely not a Christian and definitely not a brother in Christ)

(I am not requesting here others' personal views. I really want to know how this very important matter is presented in the New Testament.
This matter is in fact a fundamental matter pertaining to Christian faith. It's not like "Is smoking cigarettes good or bad according to the New Testament?" While smoking may not be an important issue in Christianity, the matter that I am concerned about here definitely is)

  • You're not going to find a list of traits that absolutely define a Christian because to be honest we're all working on becoming Christian or true followers of Christ. – James Mertz Sep 2 '11 at 13:08
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    @KronoS - Well, at least there should be a list of traits a person's lack of which would definitely exclude such a person from among Christians and brothers in Christ. For example, faith in the existence of God - if there is a person who does not believe that God exists, this person is definitely not a Christian and definitely not a brother in Christ. And that's exactly what I am asking about. Please read my question again. – brilliant Sep 2 '11 at 13:39

The New Testament gives us a very clear picture of the difference between Christian and a non-Christian in the story below. Jesus here is being crucified and two criminals are being crucified at the same time, on either side of Him.

One of the criminals who hung there hurled insults at him: “Aren’t you the Messiah? Save yourself and us!”

But the other criminal rebuked him. “Don’t you fear God,” he said, “since you are under the same sentence? We are punished justly, for we are getting what our deeds deserve. But this man has done nothing wrong.”

Then he said, “Jesus, remember me when you come into your kingdom.”

Jesus answered him, “Truly I tell you, today you will be with me in paradise.”

Luke 23:39-43

My reason for quoting this is that we read here the minimum requirement for becoming a Christian; and it is both necessary and sufficient. It is repenting (being sorry for wrongdoing) and asking Jesus for His mercy.

Everyone who calls on the name of the Lord will be saved.

Acts 2:21

That's it: that is the distinction. The other answers here describe the fruit that comes after the decision / change. This is fundamental - we're saved by what He (Jesus) has done, not by what we can do for Him. That's why the criminal here could turn to Jesus in his last moments of life and still enter the same paradise as the very best saint (The Parable of the Workers in the Vineyard, Matthew 20:1-16).

If you are interested, I have explained becoming a Christian in my answer to the question, How do you "Convert" somebody to Christianity?

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    (1) Thank you. Actually, I think your answer is very close to what I am after here. Exactly! It is repenting and asking Jesus for His mercy that looks to me as both necessary and sufficient requirement for becoming a Christian and a brother in Christ. Actually, this one simple requirement puts “Mormons” and “Jehovah’s witnesses” into a very awkward situation as they never call on the name of the Lord Jesus, they never pray to Him. They only pray to God the Father ending their prayers with “In the name of your – brilliant Sep 3 '11 at 5:26
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    (2) Son Jesus Christ”. They never use “Jesus” in the second grammatical person – only in the third one – and teach that praying directly to Jesus is a mistake. – brilliant Sep 3 '11 at 5:26
  • (3) However, I still have some points that are not that clear to me here. First of all, we don’t see that the criminal had faith that Jesus was God. He did consider Jesus to be a man, a righteous man, the Messiah and, perhaps, even the King and the Son of God; however, we can’t say for sure that he believed that Jesus was God Himself. – brilliant Sep 3 '11 at 5:27
  • (4) (There is one point here that actually makes that criminal quite different from anyone of us who turns to Jesus in his prayers after Jesus’ ascension: the criminal was still able to see Jesus when he was asking Him about His mercy. We, however, those who believed the gospel after Jesus’ ascension, when we first turned to Jesus we didn’t see Him. That means that we, perhaps, even subconsciously, acknowledged in our first prayer that Jesus possesses a – brilliant Sep 3 '11 at 5:27
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    @Wikis At Area 51 - Thanks for your answer. I think you do deserve the bounty for it. I didn't expect my question to be splitting into many sub-questions, but it seems that otherwise there's no other way to make the whole matter clear. So now I will be asking all those sub-questions separately here on "Stack". Thanks again. – brilliant Sep 6 '11 at 15:36

Nowhere in the New Testanment is there a clear, condensed definition of a Christian or a Brother in Christ. The definition is written throughout the new testament. But there are a few things which are stated that make it fairly clear. A Christian can be defined as someone who:

  • Thanks for your answer. So, if I understood you correctly, a person who does not believe that Jesus is God, but believes that Jesus is the Son of God (like "Mormons" and "Jehovah's witnesses") and has all the other things you've mentioned is also a brother in Christ and a Christian, right? – brilliant Sep 1 '11 at 10:43
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    One of the other things is that you must believe what the bible says, as it's the infallible word of God. In 1 Timothy 3:15 - 16 (KJV) states that "God was manifested in the flesh, justified in the Spirit, seen of angels, preached unto the Gentiles, believed on in the world, received up into glory." Meaning that Jesus IS God in the flesh. – levigideon Sep 2 '11 at 5:34
  • (1) I personally do believe in that, but the problem is that in the early manuscripts the word "God" is missing in 1 Tim 3:15-16 and instead of that it has "He who manifested..." But even if the word "God" was originally there, "Mormons" and "Jehovah's witnesses" believe that it should be understood as "god", not "God" (in original Greek manuscripts all letters were in the same case, there were no capital or small letters) meaning that Jesus is god (and is the son of God), but not God (like God the Father). So they say that – brilliant Sep 2 '11 at 11:25
  • (2) they do believe what the Bible says, as the infallible word of God, but their understanding of it is different from other Christian's understanding. – brilliant Sep 2 '11 at 11:26
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    I believe the thief who was crucified next to Christ is a brother. His life never had the opportunity to bear fruit. – Alex B Sep 2 '11 at 16:32

Matthew 16:24-25 (NRSV)

Then Jesus told his disciples, "If any want to become my followers, let them deny themselves and take up their cross and follow me. For those who want to save their life will lose it, and those who lose their life for my sake will find it.

The two imperatives are "take up your cross" and "follow me."

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    Thanks for your answer, but it's very abstract. In what way should one take up his cross? To what extend should one follow Christ? Isn't it like everyone has his own situation in life and, therefore, his own cross to take up and his own measure of following Jesus? Plus, I guess there can be a lot of false Christians who claim that they have taken up their cross and are following Jesus. In fact, I have even met some Muslims who say that they are following the steps of Jesus way closer than even some of the Christians. – brilliant Sep 2 '11 at 12:07
  • @brilliant, you asked how the New Testament defines a Christian. Leaving aside the anachronism of the word "Christian," this is what Jesus said about following him. You say it's abstract. It's not abstract at all to, for example, the crew who run the feeding program in my neighborhood. With respect, I wonder if your desire for clear bright-line criteria here reflects a hidden desire to be among "those who want to save their life." – user116 Sep 2 '11 at 12:16
  • "It's not abstract at all to, for example, the crew who run the feeding program in my neighborhood" - Can you, please, elaborate. I don't understand what you mean here. – brilliant Sep 2 '11 at 12:27
  • "I wonder if your desire for clear bright-line criteria here reflects a hidden desire to be among" - Well, I do have this desire and it's not hidden at all. Plus, I do believe that I am already among those who have eternal life through faith in Jesus. Here, however, I want exactly what you said: clear bright-line criteria for a Christian and for a brother in Christ. – brilliant Sep 2 '11 at 12:30

The Apostle's Creed should be a basic guideline for what Christians believe, and just because a group chooses to disagree with part doesn't invalidate this, as there are many groups that claimed to be following Jesus but would disagree with some major teaching.

Here is an interesting page on the Apostle's Creed, as it shows it in different languages, and if the page is correct the earliest version of this was written before 300AD.

For an example of groups that differed from the accepted early teachings you can look at the Great Heresies. On that page there is an explanation how people can differ from traditional teaching and not be a heresy:

A person must be baptized to commit heresy. This means that movements that have split off from or been influenced by Christianity, but that do not practice baptism (or do not practice valid baptism), are not heresies, but separate religions. Examples include Muslims, who do not practice baptism, and Jehovah’s Witnesses, who do not practice valid baptism.

So, to be Christian you must believe in the Apostle's Creed.

For an almost line by line discussion of the Apostle's Creed you can look at the Catechism of the Catholic Church as it will reference not just the Bible but writings of the Early Church Fathers.

People will disagree with each other on some teachings, but there are certain core beliefs all should have, but there are also areas that I think should be cut and dried, such as the non-violence teachings of Christ that many people seem to disagree with. Bill Maher summed up this quite well pointing out how some will disagree with what Jesus taught, even though it isn't what I considered core beliefs to be Christian.

  • Thank you for your answer, but one of the integer parts of the Apostles' creed is faith in the Holy Spirit, right?. If so, then what about that criminal on the cross who asked Jesus to remember him in His kingdom? Is he a brother in Christ then or not? For sure he knew nothing about the Holy Spirit (as the Spirit had not yet been sent because Jesus had not yet been glorified - John 7:39, 20:22) – brilliant Sep 6 '11 at 1:44
  • @brilliant - First, the holy spirit hadn't descended yet upon the Apostles, so it was a different standard. Next, if someone is about to die they may choose to believe, but all we have is their word that they are a brother in Christ. Generally this idea is for those living day to day. Personally, if someone follows the two greatest commandments, and love is defined by 1 Cor 13, then I give some hope that they truly love Christ. – James Black Sep 6 '11 at 21:03

I think the answer lies in the soul of each person n particular, so we cannot distinguish between a Christian and a non-Christian. Only God thoroughly knows each person, and is the only Judge. We probably should not try to identify certain people as non-Christians.

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    (1) I am not trying to check on any individual here on the matter of being a Christian. My question is not "Is mr. so-and-so a Christian or not?" I do admit the possibility that there may even be Christians among Muslims and Buddhists (in case they secretively prayed to Jesus). However, here I am attempting to clarify the teaching of the New Testament regarding the matter of what kind of people can be considered Christians and what kind of people can't. – brilliant Sep 3 '11 at 11:54
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    (2) Plus, in the NT we do have admonitions not to have any fellowship with certain people (2 John 1:10, 11; Tit. 3:10) - we need to know how to discern them, how the New Testament discerns them. – brilliant Sep 3 '11 at 11:56
  • Ok, please excuse me if I misunderstood your question. So how to discern which people we should avoid? Certainly groups, clubs or even enterprises where membership involves following rules that are definetely in contradiction with what Our Lord Jesus taught us. It is more complicated regarding individual people. – Luc125 Sep 3 '11 at 13:01
  • No problem. I am not offended at all. I remember once I was in fellowship with one brother in Christ, for quite a long time actually, until one day he told me that he didn't actually believe that Jesus was resurrected in His human body. When I asked him, how come then he was still praying to Jesus, he said that he believed that he was praying to Jesus' spirit. Now I wonder if that person is a brother in Christ at all, and in case I meet him again, whether or not I should continue having fellowship with him. – brilliant Sep 3 '11 at 13:28
  • If he is still praying to Jesus, then there is hope. He still might revert to the right faith... First, you can pray for him. Then if you think there is a chance that you can help him in his faith, without risking yours, then as his brother in Christ you have to try. But if it clearly does not work and if he keeps telling you wrong dangerous things, then you should no longer talk about religion with him. – Luc125 Sep 3 '11 at 15:25

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