How could the human race go to God if God had not come to us? How should we free ourselves from our birth into death if we had not been born again according to faith by a new birth generously given by God, thanks to that which came about from the Virgin’s womb?

– Irenaeus of Lyons, Against Heresies, IV.33.4.

This is the reason why the Word of God was made flesh, and the Son of God became Son of Man: so that we might enter into communion with the Word of God, and by receiving adoption might become Sons of God. Indeed we should not be able to share in immortality without a close union with the Immortal. How could we have united ourselves with immortality if immortality had not become what we are, in such a way that we should be absorbed by it, and thus we should be adopted as Sons of God?

 – Irenaeus of Lyons, Against Heresies, III.19.1.

New birth, becoming, communion, adoption, union, immortality. These are the poetry of Christmas and salvation. The purpose of the incarnation, revealed in the nativity of Jesus, is to establish full communion between God and humanity. This union does not, however, abolish the distinct identities of God and humanity. It makes us real, authentic, fully human. For only in God are we truly ourselves.