The Incarnation / Nativity of Jesus #9

The incarnation is the Christian doctrine that the eternal Son of God took on human flesh and was born as Jesus of Nazareth, uniting divine and human nature in one person. It stands as the hinge between the Old and New Testaments, the point at which centuries of messianic promise are understood to converge in a single historical birth. This entry treats the incarnation as a doctrine — what the church confesses about who Jesus is; for the narrative details of the nativity itself, see The Annunciation and The Birth of Jesus.

The Word Made Flesh

Rather than narrating the nativity, John’s Gospel opens with a theological prologue that states what Christians believe happened in it: “In the beginning was the Word, and the Word was with God, and the Word was God” (John 1:1), and “without him was not any thing made that was made” (John 1:3). John then declares, “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). Christian theology reads this verse as its clearest statement of the incarnation: the eternal, uncreated Word (Greek logos) entering embodied human existence (Greek sarx, “flesh”).

Matthew and Luke narrate the event John summarizes, each from a different vantage point and with different emphasis. Luke records the angel Gabriel telling Mary that “the Holy Ghost shall come upon thee, and the power of the Highest shall overshadow thee: therefore also that holy thing which shall be born of thee shall be called the Son of God” (Luke 1:35). Matthew, writing from Joseph’s side of the story, ties the virgin conception to prophecy, recording that it fulfilled what “was spoken of the Lord by the prophet,” namely that “a virgin shall be with child, and shall bring forth a son, and they shall call his name Emmanuel, which being interpreted is, God with us” (Matthew 1:22-23), a text drawn from Isaiah’s promise to King Ahaz that “a virgin shall conceive, and bear a son, and shall call his name Immanuel” (Isaiah 7:14). Neither Mark nor John narrates a birth; John’s contribution is entirely this theological framing.

The Doctrine of the Incarnation

Paul’s letters supply the other main biblical pillars of the doctrine. Writing to the Philippians, he describes Christ as one “who, being in the form of God, thought it not robbery to be equal with God: but made himself of no reputation, and took upon him the form of a servant, and was made in the likeness of men” (Philippians 2:6-7) — a self-emptying often called the kenosis. Writing to the Colossians, he calls Christ “the image of the invisible God, the firstborn of every creature,” through whom “all things were created” and “by [whom] all things consist” (Colossians 1:15-17). Together with John 1, these texts became the biblical basis for the church’s later formulation, at councils such as Nicaea and Chalcedon, that Jesus is one person with both a fully divine and a fully human nature — what historic Christian orthodoxy calls the hypostatic union, though some traditions state it differently.

Theological Significance

Commemorated by most churches at Christmas, the incarnation is understood in mainstream Christian theology not as an isolated miracle but as the necessary beginning of the redemptive mission that leads to the crucifixion and resurrection. The doctrine is also foundational to Trinitarian theology, since it holds that the second person of the Godhead added a human nature without ceasing to be fully God. Christians differ on finer points of how the two natures relate, but the core claim — that in Jesus, God is understood to have entered human history in person — is common to the historic creeds.