The incarnation is the act by which the eternal Son of God, without ceasing to be what He always was, became what He had not been: a true man. The word comes from the Latin for in flesh.
“And the Word was made flesh, and dwelt among us, (and we beheld his glory, the glory as of the only begotten of the Father,) full of grace and truth.”JOHN 1:14 · KJV
John chooses his verb with care. The Word who was in the beginning (John 1:1) was made flesh. The incarnation had a beginning in history, in the womb of the virgin Mary. The Son Himself did not. That is why Christians can say both that Jesus was born in Bethlehem and that He existed before Abraham (John 8:58).
In becoming man, the Son did not exchange deity for humanity. He took a human nature into union with His divine person. Paul says He took upon him the form of a servant (Philippians 2:7). He added; He did not lose.
Why the Son Became Man
- To redeem. God sent His Son, made of a woman, made under the law, to redeem those under the law (Galatians 4:4–5).
- To die in our place. Because we are flesh and blood, He shared the same, that through death He might destroy him that had the power of death (Hebrews 2:14).
- To be our High Priest. He was made like His brethren in all things, so that He could be a merciful and faithful High Priest (Hebrews 2:17).
- To reveal the Father. The only begotten Son has declared Him (John 1:18).
The Virgin Conception
Scripture teaches that Jesus was conceived by the Holy Spirit and born of a virgin (Luke 1:35; Isaiah 7:14). The virgin conception marks the incarnation as God's direct work and shows that the Saviour did not come from human initiative.
Guarding the Truth
Faithful Christians rejected errors on both sides. Docetism said Christ only seemed to be human. Arianism said the one who became man was not truly God. Apollinarianism denied Him a human mind. Later the state church's bishops at the Council of Chalcedon stated the biblical boundaries: one person, truly God and truly man. We affirm that statement because Scripture teaches it.
To see how the incarnation relates to Christ's eternal deity, begin with Was Jesus created?.