‘The Word became flesh and dwelt among us’ (John 1:14). The term ‘incarnation’ derives from the Latin, meaning ‘becoming-in-flesh.’ It intends to capture the truth of statements like this one, and others: ‘God [sent] his own Son in the likeness of sinful flesh’ (Rom 8:3); ‘Jesus Christ has come in the flesh’ (1 John 4:2). This does not mean that through incarnation God’s nature changed into human ‘flesh,’ but rather that human nature was ‘assumed by Divinity,’ taken on by God himself, such that ‘in that assumption nothing was lacking that belongs to human nature.’1Augustine, Enchiridion, 10:34; Outler ed., 360.
Incarnation means that in the person of the Lord Jesus Christ, the eternal Word and Son of God became man — for our health and salvation — implying both his full deity and his full humanity. At a particular point in historical time and space, the One who had his life eternally with the Father and the Spirit became fully human, possessing a physical human body, a real human soul, a human spirit, and human mind and will — a complete human personality, like ours in every respect except sin — without relinquishing his unity of nature with God.
The Eternal Son
The Person who became incarnate had already existed before his human birth. ‘He preexisted, in the absolute sense of the term. This is not true of any other human being, and it is the chief difference between Jesus and the rest of the human family.’2Fred Sanders, The Deep Things of God. Second Edition (Crossway, 2017), 90. Christ’s life as a human creature began at his conception and birth. Yet his existence precedes these, for from eternity he was the Father’s only-begotten Son. Before Abraham lived, he declared, ‘I AM’ (John 8:58), sharing glory and love with the Father before the world’s foundation (John 17:5, 24-26). Through him all things were made (John 1:3; Heb 1:2). Christ is, truly, a creature — yet before that, and at the same time, he is the Creator.
Chalcedon and Westminster
In 451 A.D. the Council of Chalcedon produced a definition of the incarnation that proved authoritative and enduring: in the person of Jesus Christ, divine and human natures are really and fully united, ‘perfect in Godhead and also perfect in manhood; truly God and truly man … without confusion, without change, without division, without separation; the distinction of natures being by no means taken away by the union, but rather the property of each nature being preserved, and occurring together in one Person.’3The Symbol of Chalcedon (October 22nd, 451); Schaff ed., Creeds of Christendom, 1:62, language slightly updated for clarity. The Westminster Confession expresses the same faith: two whole, perfect, and distinct natures were inseparably joined together in one person, ‘which person is very God, and very man, yet one Christ, the only Mediator between God and man.’4The Westminster Confession of Faith, 8.2.
Born of a Virgin
The means of the incarnation was Jesus’ conception in the womb of his mother Mary by the power of the Holy Spirit, without the agency of a man. Both Matthew (1:23) and Luke (1:27) say that Mary was a virgin at the time of Jesus’ conception; yet she was his biological mother. This event was unprecedented, unrepeated, and wholly unique — an act of God without analogy. The incarnation of God’s Son in Jesus is the grand central miracle of Christianity. ‘Every other miracle prepares for this, or exhibits this, or results from this.’5C. S. Lewis, Miracles (HarperCollins, 1947/1960), 173.
Why Did God Become Human?
Athanasius the Great famously expressed the purpose of the incarnation: ‘He, indeed, assumed humanity that we might become God. He manifested himself by means of a body in order that we might perceive the mind of the unseen Father. He endured shame from men that we might inherit immortality.’6Athanasius, On the Incarnation of the Word, 54; trans. St. Vladimir’s, 93. To the classic question ‘why did God become human?,’ the New Testament suggests a range of replies: to reveal God to humanity (John 1:18); to provide a sympathetic high priest interceding for us (Heb 4:14-16); to offer a pattern of the fullness of human life (1 Pet 2:21); to provide a substitutionary sacrifice for sins (Heb 10:1-10); and to bind up the demonic powers (1 John 3:8).7Thomas C. Oden, Classic Christianity (HarperCollins, 1992), 271 (as cited in Graham Cole, Against the Darkness (Crossway, 2019), 143).
Fully God, Fully Man
Jesus Christ, the eternal Son of God, is truly God. His deity is entailed, implied, and stated throughout the New Testament. He calmed the waves, walked on the sea, fed thousands, raised the dead, healed the sick, and cast out demons. There are some sixteen passages where the Greek word for God, Theos, may be applied to Jesus, including the most direct: ‘the Word was God’ (John 1:1); ‘My Lord and my God!’ (John 20:28); ‘the Christ who is God over all, blessed forever’ (Rom 9:5); ‘our great God and Saviour Jesus Christ’ (Titus 2:13).
Yet in and through all this, he is completely and entirely human. ‘For us and for our salvation Christ’s humanity is as important as his divinity.’8Mark Jones, Knowing Christ (Banner of Truth, 2016), 43. Jones’ broader discussion of Christ’s humanity (43-52) is well worth attention. The Gospels describe his feelings and experiences — anger, hunger, pity, affection, pain, tiredness, joy. The Saviour shared the lot of all human beings ‘in every respect’ (Heb 2:17), having ‘in every respect been tempted as we are, yet without sin’ (Heb 4:15). And yet the eternal Word was not confined within human nature: ‘the Son of God descended from heaven in such a way that, without leaving heaven, he willed to be borne in the virgin’s womb, to go about the earth, and to hang upon the cross; yet he continuously filled the world even as he had done from the beginning!’9Calvin, Institutes, 2.13.4; Battles ed., 481.
The One Mediator
Christ is called ‘mediator’ in three New Testament passages: the ‘one mediator between God and men’ (1 Tim 2:5), and ‘the mediator of a new covenant’ (Heb 9:15; 12:24). The Westminster Larger Catechism draws out why the Mediator must be God (to sustain human nature under infinite wrath, give worth to his sufferings, satisfy justice, and conquer all enemies), why he must be man (to obey the law in our nature, suffer and intercede for us, and feel our infirmities), and why he must be both in one person: ‘that the proper works of each nature might be accepted of God for us, and relied on by us as the works of the whole person.’10The Westminster Larger Catechism (Questions 38-40). To aid clarity, the language has been slightly amended.
Each nature contributes what the other cannot, and only their union in a single person secures the whole of our salvation. As Calvin concluded: ‘since neither as God alone could he feel death, nor as man alone could he overcome it, he coupled human nature with divine that to atone for sin he might submit the weakness of the one to death; and that wrestling with death by the power of the other nature, he might win victory for us.’11Calvin, Institutes, 2.12.3; Battles ed., 466-67. Because he himself suffered when tempted, he is able to help those who are being tempted (Heb 2:18). As our mediator he is praying for us at the right hand of the Father, even now.
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- 1Augustine, Enchiridion, 10:34; Outler ed., 360.
- 2Fred Sanders, The Deep Things of God. Second Edition (Crossway, 2017), 90.
- 3The Symbol of Chalcedon (October 22nd, 451); Schaff ed., Creeds of Christendom, 1:62, language slightly updated for clarity.
- 4The Westminster Confession of Faith, 8.2.
- 5C. S. Lewis, Miracles (HarperCollins, 1947/1960), 173.
- 6Athanasius, On the Incarnation of the Word, 54; trans. St. Vladimir’s, 93.
- 7Thomas C. Oden, Classic Christianity (HarperCollins, 1992), 271 (as cited in Graham Cole, Against the Darkness (Crossway, 2019), 143).
- 8Mark Jones, Knowing Christ (Banner of Truth, 2016), 43. Jones’ broader discussion of Christ’s humanity (43-52) is well worth attention.
- 9Calvin, Institutes, 2.13.4; Battles ed., 481.
- 10The Westminster Larger Catechism (Questions 38-40). To aid clarity, the language has been slightly amended.
- 11Calvin, Institutes, 2.12.3; Battles ed., 466-67.