The Incarnation is the foundational mystery of Christianity. The eternal Son of God — co-equal with the Father, the agent of all creation — took on human flesh and was born of the Virgin Mary. He was not a man who became divine (that is adoptionism). He was not God appearing to be human (that is docetism). He was not God minus some divine attributes (that is kenotic theology in its heretical form). He was not a hybrid or blending of natures (that is Eutychianism). The classical Christian doctrine, codified at the Council of Chalcedon in 451 AD, is that Christ is "one person in two natures" — fully God and fully man — "without confusion, without change, without division, without separation." John states it most compactly: "In the beginning was the Word, and the Word was with God, and the Word was God... And the Word became flesh and dwelt among us" (John 1:1, 14). Paul states it most movingly: "Let this mind be in you which was also in Christ Jesus, who, being in the form of God, did not consider it robbery to be equal with God, but made Himself of no reputation, taking the form of a bondservant, and coming in the likeness of men" (Philippians 2:5-7). Why does the Incarnation matter? Because only God can save, but only man can stand in our place as representative. Christ had to be fully God to accomplish redemption and fully man to accomplish it for us. "Since therefore the children share in flesh and blood, He Himself likewise partook of the same things, that through death He might destroy the one who has the power of death, that is, the devil, and deliver all those who through fear of death were subject to lifelong slavery" (Hebrews 2:14-15). The Incarnation did not end at the ascension. Christ still has His human body — now glorified — and He will forever be the God-man, mediating between God and men.