Incarnation

“And the Word became flesh and dwelt among us, and we have seen his glory, glory as of the only Son from the Father, full of grace and truth.” — John 1:14

The incarnation is the miracle by which the eternal Son of God took on a true human nature, being born of the Virgin Mary, without ceasing to be God. He became what He was not while remaining what He always was.

The Mystery

The incarnation does not mean:

• God turned into a man (the divine nature was not lost)
• A man became God (Jesus did not start as merely human)
• Two persons inhabited one body (He is one person with two natures)

Rather, the second person of the Trinity assumed a human nature — body and soul — into personal union with Himself. As Athanasius declared in De Incarnatione, “The Word was not degraded by receiving a body… He deified what He put on” (54.3) — the incarnation elevates humanity without diminishing divinity.

The Virgin Birth

The incarnation began with a miraculous conception. Isaiah prophesied that a virgin would conceive and bear a son called Immanuel — “God with us” (Isaiah 7:14; Matthew 1:23).

The Hebrew word almah (עַלְמָה) means “young woman of marriageable age,” while the Greek Septuagint translates it as parthenos (παρθένος) — “virgin.” Matthew, writing under the Spirit’s inspiration, affirms the meaning the Septuagint expressed: Mary conceived without a human father, by the power of the Holy Spirit (Matthew 1:18–20; Luke 1:34–35).

The angel Gabriel announced to Mary: “The Holy Spirit will come upon you, and the power of the Most High will overshadow you; therefore the child to be born will be called holy — the Son of God” (Luke 1:35).

The virgin birth safeguards two truths: the Son’s divine origin (He was not generated by human will) and His true humanity (He was genuinely born of a woman, Galatians 4:4).

The Hypostatic Union

The church confesses that in Christ two complete natures — divine and human — are united in one person, or hypostasis (ὑπόστασις). This term, meaning “underlying reality” or “subsistence,” was adopted to express that Christ is not two persons acting in concert, but one divine-human person.

The divine nature is complete: omnipotent, omniscient, eternal, infinite. The human nature is complete: body, soul, mind, will, human emotions and limitations. These two natures belong to one person — the eternal Son — without either nature being diminished.

The Chalcedonian Definition

The Council of Chalcedon (451 AD) articulated this mystery with careful precision, declaring that Christ’s two natures exist in one person:

“without confusion, without change, without division, without separation”

• Without confusion — the natures do not blend into a third thing
• Without change — neither nature is altered by the union
• Without division — the natures are not parceled into separate compartments
• Without separation — the natures are never pulled apart; wherever Christ is, both natures are present

These four fences guard the mystery from every direction. The Chalcedonian Definition remains the standard of orthodox Christology across Catholic, Orthodox, and Protestant traditions. For the historical development of this formula and the heresies it was designed to exclude, see the companion articles.

The Kenosis

Paul’s hymn in Philippians 2:5–11 describes the self-emptying of the Son:

“Who, though he was in the form of God, did not count equality with God a thing to be grasped, but emptied himself, by taking the form of a servant, being born in the likeness of men.” — Philippians 2:6–7

The Greek kenosis (κένωσις), from kenoō (κενόω) — “to empty,” does not mean Christ surrendered His divine attributes. He remained omnipotent, omniscient, and omnipresent in His divine nature. Rather, He emptied Himself by addition: taking on the form of a servant, veiling His glory in human flesh, and voluntarily refraining from the independent exercise of certain divine prerogatives during His earthly ministry.

The kenosis is descent, not diminishment. The Son did not become less God; He became also man. The one who sustains the universe by the word of His power (Hebrews 1:3) lay as an infant in a manger, nursed at His mother’s breast, and grew in wisdom and stature (Luke 2:52).

Why Both Natures Are Essential

The incarnation was necessary for salvation:

1. Only God can save — no creature can bear the infinite weight of divine wrath (cf. atonement)
2. Only a man can represent humanity — our substitute had to be one of us (Hebrews 2:14–17; cf. the Adamic federal headship)
3. Only the God-man unites us to God — Christ is the mediator between God and man (1 Timothy 2:5), the bridge between Creator and creature

If Christ were not truly God, His sacrifice would be insufficient — a finite being cannot atone for infinite offense. If He were not truly man, His sacrifice would be irrelevant — He could not stand in our place. If the two natures were confused or separated, the mediatorial work would collapse.

The whole of salvation hangs on the truth that Jesus Christ is one person in two natures, fully God and fully man, now and forever. The incarnation is not merely a past event but an enduring reality: the risen and ascended Christ retains His human nature for all eternity, guaranteeing that humanity has a permanent representative at the Father’s right hand (Hebrews 7:25) and that the image of God will be brought to its fullest expression in the new creation.

“For there is one God, and there is one mediator between God and men, the man Christ Jesus.” — 1 Timothy 2:5