In order to have a more complete grasp of Christ’s incarnation, it is necessary to have some sort of understanding of the Trinity. The doctrine of the Trinity states that God is one being, and this one God exists as three distinct Persons. This truth means, first of all, that we must distinguish each Person of the Trinity from the other two. The Father is not the Son or the Holy Spirit, the Son is not the Holy Spirit or the Father, and the Holy Spirit is not the Father or the Son. They are each a distinct center of consciousness, a distinct form of personal existence. Yet, they all share the exact same divine nature/essence. Thus, the three persons are one being. The divine being/essence is not something that is divided between the Persons with each Person receiving one-third. Rather, the divine being is fully and equally possessed by all three Persons such that all three Persons are each fully and equally God.
The Bible teaches that Jesus is not merely someone who is a lot like God, or someone who has a very close walk with God. Rather, Jesus is the Most High God himself. Titus 2:13 says that as Christians we are “looking for the blessed hope and the appearing of the glory of our great God and Savior, Christ Jesus.” Upon seeing the resurrected Christ, Thomas cried out, “My Lord and my God!” (John 20:28). Likewise, the book of Hebrews gives us God the Father’s direct testimony about Christ: “But of the Son he says: "Your throne, O God, is forever and ever" and the gospel of John calls Jesus “the only begotten God” (John 1:18).
The first truth we need to understand is that Jesus is one Person who has two natures: a divine nature and a human nature. In other words, Jesus is both God and man. John explains this incarnation in John 1:1 where he says:
“In the beginning was the Word, and the Word was with God, and the Word was God.”
He goes on in John 1:14 to say:
“And the Word became flesh and dwelt among us, and we beheld his glory, glory as of the only begotten from the Father, full of grace and truth.”
The Word referred to here is Jesus Christ who is God the Son. It should be obvious that if Jesus is God, then he has always been God. There was never a time when he became God, for God is eternal. But Jesus has not always been man.
He became man when he took on the human nature.
At Jesus’ baptism we see the Father affirming, in Luke 3:22:
“You are my beloved Son, in You I am well pleased”
He did not say, “You are me, and with myself I am well pleased.” Rather, the Father affirmed that Jesus is the Son, his Son, and that Jesus is well pleasing to him. In this same verse we also see that the Holy Spirit is distinct from the Father and the Son, for the Holy Spirit is present in “bodily form like a dove.”
But what exactly do we mean when we say that God the Son became man?
When we say that God the Son became man, we certainly do not mean that he turned into a man in the sense that he stopped being God and started being man. Jesus did not give up any of his divinity in the incarnation.
It is also important to recognize that when we say that Jesus is man, we do not simply mean that he is partially man. We mean that he is fully human — everything that belongs to the essence of true humanity is true of him. He is just as truly human as the rest of us. The fact that Jesus is truly and fully human is clear from the fact that he has a human body (Luke 24:39), a human mind (Luke 2:52), and a human soul (Matthew 26:38). Jesus does not just look like a man. He does not just have some aspects of what is essential for true humanity but not others. Rather, he possesses full humanity.
For most people it is obvious that Jesus will be God forever. But for some reason it escapes a lot of us that Jesus will also be man forever. He is still man right now as you read this and will be forever. The Bible is clear that Jesus rose physically from the dead in the same body that had died (Luke 24:39) and then ascended into heaven as a man in his physical body (Acts 1:9; Luke 24:50–51). It would make no sense for him to have done this if he was simply going to ditch his body and stop being man when he arrived in heaven.
That Christ continued being man with a physical body after his ascension is confirmed by the fact that when he returns, it will be as a man in his body. He will return physically.
Philippians 3:21 says that at his second coming, Christ “will transform the body of our humble state into conformity with the body of his glory.” This verse is clear that Jesus still has his body. It is a glorified body, which Paul calls, “the body of his glory.” And when Christ returns, he will still have it because this verse says that he will transform our bodies to be like his. Both Jesus and all Christians will then continue living together in their bodies forever, because the resurrection body cannot die (1 Corinthians 15:42) since it is eternal (2 Corinthians 5:1).
Why did Jesus become man, and why will he be man forever?
The book of Hebrews says it was so that Christ could be an adequate Savior who has all that we need. “He had to be made like his brothers in all things, that he might become a merciful and faithful high priest in things pertaining to God, to make propitiation for the sins of the people” (2:17).
First, notice that Jesus became man so that he could die for our sins. He had to be human in order to pay the penalty for humans. Second, this verse says that because Jesus is human like us, he is able to be a merciful and faithful High Priest. His humanity enables him to more fully sympathize with us and identify with us. I cannot help but believe that it is very destructive to our comfort and faith to not know that Jesus is still man and in his body. For if he is not still man in heaven, how could we have comfort knowing that he can fully sympathize with us? He can sympathize and be a faithful high priest and know what we are going through not just because he was once on earth as a man, but because he continues forever as that same man.
Because Jesus is man, he has experienced the same things that we do. Because he is man, he can identify with us more intimately. Because he is man, he can come to our aid as our sympathetic High Priest when we reach the limits of our human weaknesses. Because he is man, we can relate to him — he is not far off and uninvolved. Because he is man, we cannot complain that God does not know what we are going through. He experienced it firsthand.
The truths of Christ’s two natures — his full manhood and full Godhood — are pretty well understood and known by Christians. But for a right understanding of the incarnation we must go even further. We must understand that the two natures of Christ remain distinct and retain their own properties. What does this truth mean? Two things: (1) They do not alter one another’s essential properties and (2) neither do they mix together into a mysterious third kind of nature.
First, it would be wrong to think that Christ’s two natures mix together to form a third kind of nature. This is one of the heresies that the early church had to fight. This heresy taught that the human nature of Christ was taken up and absorbed into the divine nature, so that both natures were changed somewhat and a third kind of nature resulted. An analogy to [this] can be seen if we put a drop of ink in a glass of water: the mixture resulting is neither pure ink nor pure water, but some kind of third substance, a mixture of the two in which both the ink and the water are changed. Similarly, [this view] taught that Jesus was a mixture of divine and human elements in which both were somewhat modified to form one new nature.5
This view is un-biblical because it demolishes both Christ’s deity and humanity. For if Christ’s two natures mixed together, then he is no longer truly and fully God and truly and fully man, but is some entirely different kind of being that resulted from a mixture of the two natures.
Second, even if we acknowledge that the natures do not mix together into a third kind of nature, it would also be wrong to think that the two natures changed one another. For example, it would be wrong to conclude that Jesus’ human nature became divine in some ways or that his divine nature became human in some ways. Rather, each nature remains distinct and thereby retains its own individual properties and does not change.
What we have seen so far about the deity and humanity of Christ shows us that Christ has two natures — a divine nature and a human nature — that each nature is full and complete, that they remain distinct and do not mix together to form a third kind of nature, and that Christ will be both God and man forever.
But if Christ has two natures, does this mean that he is also two people?
No, it does not. Christ remains one person. There is only one Christ. The church has historically stated this truth in this way: Christ has two natures united in one person forever.
At this point we find another heretical view to beware of. This view, while acknowledging that Jesus is fully God and fully man, denies that he is only one Person. According to this view, there are two separate persons in Christ as well as two natures. In contrast to this, the Bible is very clear that, while Jesus has two natures, he is only one Person. In other words, what this means is that there are not two Jesus Christ’s. In spite of the fact that he has a duality of natures, he is not two Christ’s, but one. While remaining distinct, the two natures are united together in such a way so as to be one Person. We have many instances in Scripture which demonstrate this reality. For example, Jesus says in John 8:58, “. . . before Abraham was, I am.” Now, Christ’s human nature did not exist before Abraham. It is Christ’s divine nature that eternally exists before Abraham. But since Christ is one Person, he could say that before Abraham was, he is.
The union of Christ’s deity and humanity in one Person makes it such that we have all that we need in the same Savior. How glorious! Because Jesus is God, he is all-powerful and he cannot be defeated. Because he is God, he is the only adequate Savior. Because he is God, believers are safe and can never perish; we have security. Because he is God, we can have confidence that he will empower us for the task that he commands us for. And because he is God, all people will be accountable to him when he returns to judge the world.