Q. There are numerous quotes in the New Testament that state that Christ lives in us. But they all seem to predicate this on a belief in Jesus. But if we are all children of God, doesn’t God (and, therefore, Jesus) live in all humans, believers and unbelievers alike?
I would say that in one sense Jesus lives in everyone, but that Jesus lives in another sense only in those who believe in him and trust him for salvation.
Christian theology recognizes that God is paradoxically both transcendent and immanent. That means that while God is a being separate from what he created (Christianity is not pantheistic), God is also present within his creation, including in the people he created. The New Testament affirms this. Paul told the Athenians, for example, “He is not far from any one of us,” and then he quoted the Greek poet Epimenides, “In him we live and move and have our being.” Paul wrote to the Colossians that the church of Christ is “his body, the fullness of him who fills all in all.” I will comment on the first part of that statement shortly, but in the second part of it, Paul is saying that Christ “fills all in all.” English versions express the meaning of that by saying things such as that he “fills everything in every way” or that he “fills everything everywhere with himself.” So Christ does live in all humans immanently.
However, the New Testament seems to distinguish a different sense in which Christ lives specifically in those who believe in him. Paul wrote to the Galatians, “I have been crucified with Christ; nevertheless, I live, yet not I, but Christ lives in me, and the life that I now live in the flesh, I live by the faith in the Son of God, who loved me and gave himself for me.” We see here that Christ living in a person in this sense is the result of that person surrendering his life to Christ. The idea is similar in what Paul wrote to the Corinthians: “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?” The clear implication is that if people are “in the faith,” then Christ lives in them in this sense, but not otherwise.
So what is the sense—different from the immanent sense in which Christ lives in everyone—in which Christ lives in believers? I would say that it is a relational sense. Paul wrote to the Philippians that his goal was “that I may gain Christ and be found in him, not having a righteousness of my own that comes from the law, but that which comes through faith in Christ, the righteousness from God that depends on faith—that I may know him and the power of his resurrection, and may share his sufferings, becoming like him in his death, if by any means I may attain the resurrection from the dead.” It seems that Paul equates “being found in Christ” (which I would say is comparable with Christ living in him) with “knowing him.” I think he means close personal fellowship. Jesus himself used this same image for belief in the message he gave John for the Laodicean church: “Behold, I stand at the door and knock. If anyone hears my voice and opens the door, I will come in to him and eat with him, and he with me.” I think it is in this sense that Paul tells the Colossians that the church is the “body” and the “fullness” of Christ. It is the human community that he inhabits in the fullest way.
So I would say that while it is true that Christ lives in everyone in an immanent sense, Christ lives only in believers in a relational sense.
Good Question 