She will bear a son, and you shall call his name Jesus, for he will save his people from their sins.

Matt 1:20-21

The doctrine of the incarnation means that Jesus Christ, the eternal Word, is God in human flesh. The great act of God: the second person of the Trinity, the Son of God, took upon himself our nature (Phil. 2:6-7). The incarnation is the miraculous bringing together of humanity and divinity in a single person, the Lord Jesus Christ. As Wayne Grudem stated so succinctly, “Jesus Christ was fully God and fully man in one person, and will be so forever” (Systematic Theology, 529). Meditate on these thoughts: God in all his glory, came down from heaven and took on the all vulnerabilities and weaknesses of a newborn child: crying, wetting, hungry, and pooping.

The divine Son became a Jew; the Almighty appeared on earth as a helpless human baby, unable to do more than lie and stare and wriggle and make noises, needed to be fed and changed and taught to talk like any other child . . . The more you think about it, the more staggering it gets.

J. I. Packer