When the eternal Word and Son of God “became flesh and dwelt among us” (John 1:14), God decided in his omnipotent freedom to become who we are, without ever ceasing to be fully who He has always been, and always will be. In the miracle of Christmas, God became a fully human being in swaddling clothes, even as He remained the Lord of the universe. When God the Son became incarnate he entered into the deepest ground of our human existence, to forever live his divine life in our human nature. He did this in order to grant us a life-giving, life-transforming share in His communion with the Father through the Holy Spirit, the glorious first-fruits of his reconciling all things in heaven and earth in Himself (Eph. 1:10; Col. 1:20). The nineteenth century Reformed theologian and churchman John Williamson Nevin thus exclaims:
“The Word became flesh!” In this simple, but sublime enunciation, we have the whole gospel comprehended in a word … The incarnation is the key that unlocks the sense of all God’s revelations. It is the key that unlocks the sense of all God’s work’s, and brings to light the true meaning of the universe … The incarnation forms thus the great central fact of the world.