The Incarnation

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In the sixth century, in an icon at the monastery of Saint Catherine at the foot of Sinai, a painter set down a face that has never quite settled. The two halves of it do not match. One eye is serene, the brow smooth; the other is shadowed, the cheek drawn, the mouth pulled fractionally down. Viewers have read the right side as the judge and the left as the man of sorrows, the divine and the human held in a single countenance that refuses to resolve into one or the other. The icon is older than most of the words used to describe what it shows. By the time it was painted, the church had already spent three centuries trying to say, without contradicting itself, who exactly was looking back.

Christ Pantocrator, encaustic on panel, Saint Catherine’s Monastery, Mount Sinai, 6th century. — via Wikimedia Commons (public domain)

The doctrine of the Incarnation is the claim that the eternal Son of God, the divine Word through whom all things were made, became a particular human being — Jesus of Nazareth — without ceasing to be God. Not a god in disguise, not a man adopted into divinity, not a hybrid of the two: one person, fully divine and fully human. The Latin term, incarnatio, renders the Greek of the Gospel of John literally — a becoming-flesh. Almost everything difficult in classical Christian thought follows from taking that sentence seriously and refusing every easier reading of it.

The witness and its working-out

The seed text is a single line. The prologue of the Gospel of John, after twelve verses on the Word who was with God and was God, turns abruptly to history: “And the Word became flesh and dwelt among us.” The Greek for “flesh,” sarx, is deliberately coarse — not “took a body,” not “appeared as a man,” but became flesh, the perishable stuff of human life. The same Gospel insists the Word is the agent of creation; the scandal is that this agent now has a birthplace and a death.

Beside John stands an older fragment, embedded by Paul in his letter to the Philippians and widely held by scholars to predate the letter — a hymn the apostle quotes rather than composes. It describes one who, “though he was in the form of God, did not regard equality with God as something to be exploited, but emptied himself, taking the form of a servant, being born in human likeness.” The verb at its center, ekenōsen, “he emptied,” would give later theology one of its most contested words: kenosis, the self-emptying of the divine. Paul elsewhere phrases the movement as God’s own initiative — God “sending his Son,” born of a woman, born under the law. The direction of travel is from above downward. Divinity is not climbed up to; it descends.

For two centuries these claims circulated faster than their grammar could be fixed, and rival readings multiplied. Some held that the divine Word only seemed to suffer and die, the body a phantom — the position the tradition came to call docetism, and which the various Gnostic schools often pressed toward, repelled by the idea that a pure spiritual principle could touch matter. Others moved in the opposite direction, treating Jesus as a man so filled with God as to be adopted into sonship. The Word, whose very name carried the freight of Greek philosophy — the Logos that ordered the cosmos, refined in the Judaism of Philo of Alexandria and in the Platonist and Neoplatonist schools that shaped the Christian theologians — sat uneasily inside a single Galilean life. To say the Logos was born and died seemed to make the unchanging change, the impassible suffer. The councils were the church’s attempt to keep the paradox and reject the resolutions that dissolved it.

Nicaea, Ephesus, and the first half of the question

The first great council met at Nicaea in 325, summoned by the emperor Constantine to settle a dispute that had split the eastern church. The presbyter Arius of Alexandria had taught that the Son, however exalted, was a creature — brought into being, “there was when he was not,” subordinate to and other than the unbegotten Father. Against this the council inserted into its creed a single non-scriptural Greek word, homoousios, “of one substance”: the Son is “true God from true God, begotten not made, of one substance with the Father.” The word was contested precisely because it was not in scripture, and the decades after Nicaea were anything but settled. But the principle held. Whatever the Incarnation was, it was God himself, not a demigod or a privileged creature, who had entered human life.

Icon of the First Council of Nicaea, with the bishops and the text of the creed. — via Wikimedia Commons (public domain)

Nicaea answered who the Son was in relation to the Father; it left open how the divine and human held together in Jesus. That question came to a head a century later in the clash between two patriarchs. Nestorius of Constantinople objected to a title long given to Mary in popular devotion: Theotokos, “God-bearer,” the one who gave birth to God. He preferred Christotokos, “Christ-bearer.” His worry was reverent — how could the eternal God be born, be an infant, be nursed? — but it implied that the one born of Mary and the divine Word were, at some level, two distinct subjects loosely conjoined. Cyril of Alexandria saw in this a Christ split down the middle, two persons acting in concert rather than one. The Council of Ephesus in 431, presided over by Cyril, condemned Nestorius and affirmed Theotokos: Mary bore not merely a man, nor merely God’s deputy, but the one person who is God incarnate. The council also reaffirmed the Nicene faith and forbade the composition of any new creed.

The logic behind Theotokos is what later theology named the communicatio idiomatum, the communication of idioms or properties. Because the natures belong to one person, what is true of either nature may be said of the person. God can be said to have been born; the man Jesus can be said to have existed before Abraham. The properties are exchanged at the level of the person without being confused at the level of the natures — a rule of speech that lets the tradition say “God died on the cross” without meaning that divinity perished.

Chalcedon and the formula that drew the line

Ephesus had defended the unity of the person, but its language — Cyril’s slogan of “one nature of the Word incarnate” — could be read as collapsing the human into the divine, and a monk named Eutyches did so read it, teaching that Christ’s humanity was absorbed into his deity like a drop of wine in the sea. The corrective came at the fourth and most consequential council, held at Chalcedon, across the water from Constantinople, in 451. Drawing on a doctrinal letter from Pope Leo of Rome known as the Tome, the assembled bishops issued a definition that has governed the question ever since.

Christ, the definition states, is to be acknowledged “in two natures, without confusion, without change, without division, without separation.” The distinction of the natures — divine and human — is not abolished by their union; rather the property of each is preserved, and both concur in one person and one hypostasis, one concrete subject. The four negatives at the center of the Chalcedonian Definition are the heart of it, and they cut in two directions at once. Without confusion and without change deny Eutyches: the divine does not melt the human, nor the human dilute the divine. Without division and without separation deny Nestorius: the one Christ is not pulled apart into two acting subjects. The natures are two; the person is one. This is the hypostatic union — a union not of two things into a third, but of two complete natures in a single eternal who.

Vasily Surikov, the Fourth Ecumenical Council of Chalcedon, 1876. — via Wikimedia Commons (public domain)

What Chalcedon offered was less an explanation than a fence. It did not say how two natures inhere in one person — the mechanism remains, from inside the tradition, a mystery proper to God. It said only where the explanation must not go: not toward a single blended nature, not toward two persons. The genius and the limit of the definition are the same. It secures the paradox by ruling out the comfortable simplifications on either side, and leaves the believer holding both ends of a claim that cannot be made to lie flat.

What the doctrine is for

For the church fathers the Incarnation was never a metaphysical curiosity. It was the hinge of salvation, and the reasoning ran in a tight circle that the tradition has never tired of tracing. Athanasius of Alexandria, the great defender of Nicaea, put it in a sentence that became the watchword of the whole soteriology: in the fifty-fourth chapter of his treatise On the Incarnation, the Word, he wrote, “became man that we might become god.” The descent of God into humanity opens an ascent of humanity into God. What is not assumed is not healed; therefore the Word took on the whole of human nature — body, soul, mind, mortality — so that the whole might be redeemed and, in the language of the Greek fathers, deified. This is the doctrine of theosis, divine-human participation, sometimes rendered in the West as deification or apotheosis: humanity becomes, by grace, what God is by nature. The Incarnation and the destiny of the saved are two ends of one arc.

Gregory of Nazianzus sharpened the principle into a polemical edge — the unassumed is the unhealed — and Maximus the Confessor and John of Damascus built it into vast syntheses in which the union of natures in Christ is the pattern and the pledge of the union between God and creation. The kenosis of the hymn in Philippians supplies the other half of the rhythm: God empties himself downward so that the emptied may be filled upward. The motion that looks like loss — the eternal taking on time, the impassible taking on a death — is read, from inside the frame, as the very means of the world’s repair.

The Incarnation is also inseparable from the doctrine of the Trinity, and the two were hammered out in the same furnace. It is precisely the second person of the Trinity, the Word, who becomes incarnate — not the Father, not the Spirit. The triune God is the grammar that makes the sentence “God became man” sayable without making God a creature: God is not exhausted by the man Jesus, for the Father remains unincarnate and the Son who empties himself does not cease to fill all things.

Dissent, schism, and the afterlife of a formula

Chalcedon settled the dogma of the imperial church, but it also broke it. To a large body of Christians in Egypt, Syria, and Armenia, the council’s “in two natures” sounded like a betrayal of Cyril and a back door to Nestorius. They held instead to “one united nature of the Word incarnate” — mia physis, from which their later name, miaphysite — insisting that after the union the divine and human in Christ form a single composite nature, neither confused nor divided. These churches, the Coptic, the Syriac, the Armenian, the Ethiopian, and their kin, refused the council and became the communion now called Oriental Orthodox; from their side the council was long remembered as a calamity. They reject the label “monophysite,” with its implication that Christ’s humanity was swallowed up, and they condemned Eutyches as firmly as the Chalcedonians did. The quarrel turned in large part on a single word, physis, “nature,” which the two sides did not use in the same sense.

At the other pole stood the Church of the East, centered in Persia beyond the Roman frontier, which honored the dyophysite tradition associated with Nestorius and developed its own rich Christology of two natures and, in its strong forms, two qnome, concrete instances. Often called Nestorian by its opponents, it carried this theology along the trade roads as far as India and China. The result, by the close of antiquity, was three enduring Christological families — Chalcedonian, miaphysite, and the Church of the East — divided less by whether the Incarnation happened than by how the joining of God and man is best spoken. Modern dialogue has narrowed many of the gaps, with several parties concluding that the ancient anathemas struck at words more than at meanings.

In the medieval West the question shifted from how to why. Around 1098 Anselm of Canterbury wrote Cur Deus Homo, “Why God Became Man,” a dialogue arguing the necessity of the Incarnation on its own terms, setting aside, for the sake of argument, the authority of scripture. His answer became the satisfaction theory of the atonement. Human sin is an infinite affront to the honor of an infinite God; the debt is one that humanity owes but cannot pay, and that God could remit but justice will not let him simply waive. Only a being who is both human, and so rightly liable for the debt, and divine, and so able to pay something of infinite worth, can make satisfaction. Hence God must become man. The argument recast the Incarnation as the solution to a problem in divine justice — a framing that would dominate Western soteriology and, much later, draw the criticism that it reads the cross through the lens of feudal law.

The modern period reopened the older questions under new pressure. Nineteenth-century kenotic theologians, taking the Philippians hymn at its starkest, proposed that the incarnate Word genuinely set aside some divine attributes — omniscience, omnipresence — for the duration of the earthly life, a reading the patristic tradition had been careful to avoid. The historical-critical study of the Gospels, meanwhile, drove a wedge between the Jesus of Galilee reconstructed by scholarship and the cosmic Word of the creeds, and much of twentieth-century theology was occupied with whether and how the two could be the same figure. Through all of it the Chalcedonian fence has held its strange shape: a definition that explains nothing and forbids almost everything, leaving the face in the icon exactly as the painter left it — one person, looking out of two natures, the join visible and the seam refusing to close.

→ Related: Trinity · Logos · Jesus Christ · Hypostasis · Athanasius · Arius · Nestorius · Anselm Of Canterbury · Apotheosis · Neochalcedonian Christology · Gregory Of Nazianzus · Maximus The Confessor · John Of Damascus · Docetism · Gnosticism · New Testament · Philo Of Alexandria · Platonism · Neoplatonism · Plotinus