The Inconfusion of the Two Natures in Christ: Against Monophysitism

The Hypostatic Union has two essential elements: the union of Christ’s manhood with the Divine Person of the Logos, and the existence of that one Divine Person in two perfect natures, united but unmixed. Any commingling of the two natures, after the manner of a natural compound, would be incompatible with the Hypostatic Union. The Nestorians denied Christ’s personal unity by overstating the duality; the Monophysites went to the opposite extreme, confounding the two natures altogether. The Catholic Church holds the mean between both errors, affirming unity in duality and duality in unity at once.

The Heresy of Eutyches and the Church’s Teaching

Eutyches, an archimandrite of Constantinople who had defended Christ’s unity nobly at Ephesus in 431, tried to reinforce his own position by claiming Christ has only one nature — since otherwise, he thought, Christ could not strictly be one Hypostasis. He appealed to St. Cyril’s own formulas — “a natural union” and “one incarnate nature of the Word” — as supporting his view.¹

Eutyches found a powerful protector in Dioscorus, then disgracing the episcopal see once held by Athanasius and Cyril. At a council held at Ephesus in A.D. 449 — later known as the “Robber Synod” — Eutyches was declared orthodox and the bishops who opposed him deposed, a result that helped spread the new heresy through Egypt, Palestine, Syria, and Armenia. Though united in holding “one nature,” the Monophysites soon split over exactly how Godhead and manhood are united in Christ: some held the humanity was simply absorbed into the Godhead; others that the two natures fused into one; a third, intermediate group held the union resembled that of body and soul in man. Various Monophysite sects followed — the Acephali, the followers of Peter the Fuller (Theopaschites), the Severians, the Julianists, the Jacobites — some of which survive to this day among the Copts of Egypt and the Jacobites of Syria and Mesopotamia.²

Catholic orthodoxy found its great defender in Pope St. Leo the Great, whose Epistula Dogmatica ad Flavianum stated the Catholic doctrine so clearly that the bishops assembled at Chalcedon in 451 cried out, “Peter has spoken through the mouth of Leo.”³ Chalcedon affirmed both the hypostatic unity of Christ and the existence of two unmixed natures in the one Divine Person, defining that Christ exists in two natures, “indivisible and inseparable” yet at the same time “unchanged and inconfused” — the indivisible unity of Person in no way destroying the distinction between the two natures or the properties proper to each.⁴

The Teaching of Revelation

The Scriptural case for Christ’s Divinity and humanity already outlined earlier in this treatise sufficiently refutes Monophysitism along with Nestorianism.

The Scriptural Argument

By constantly presenting our Savior as both true God and true man, the New Testament implicitly rules out the notion that He is some blend or confusion of natures — such a being would be neither God nor man. St. Paul treats “the form of God” and “the form of a servant” as distinct even while hypostatically united in the one Christ, “who, being in the form of God, took the form of a servant” (Philippians 2:6-7). Only because Godhead and manhood coexist in Christ as two inseparable yet unchanged and unconfused natures could He say, “I and the Father are one” (John 10:30) as God, and “The Father is greater than I” (John 14:28) as man. St. Augustine draws out the implication: “He did not so take the form of a servant that He lost the form of God, in which He was equal to the Father. If, then, the form of a servant was taken in such a way that the form of God was not lost — since in both the form of a servant and the form of God He is the same only-begotten Son of God the Father, equal to the Father in the form of God, and the mediator between God and men, the man Christ Jesus, in the form of a servant — who fails to see that He, in the form of God, is greater even than Himself, and yet, in the form of a servant, likewise less than Himself?”⁵ And “the Word was made flesh” (John 1:14) not only describes the Hypostatic Union of the Logos with human nature, but implies that both natures remained perfect in their own kind, both after and despite the union.

The Patristic Argument

The Fathers before Chalcedon believed in the unconfused coexistence of both natures in Christ as an article of faith.

St. Athanasius exclaims: “What hell has produced the claim that the body born of Mary is consubstantial with the Godhead of the Logos? Or that the Logos was changed into flesh, bone, hair, and the whole body, and so lost His own nature?”⁶ St. Gregory of Nazianzus similarly: “God came also as a mortal man, combining two natures into one [Person] — not into one nature — the one hidden, the other manifest to men.”⁷ St. Ephraem the Syrian gives the doctrine sublime expression: “He has a perfect twofold nature, lest He lose either of the two. For God was not seen on earth in one nature alone, nor did man ascend into heaven in the other alone; but perfect from the Perfect, man from man, God from God, Christ from the Virgin.”⁸ St. John Damascene, our chief later authority for this whole tradition, writes: “If there is but one nature in Christ, how can He be consubstantial with both His Father and His mother? The one is God, the other [Mary] a human being. But God and man do not share one nature.”⁹ In the West, St. Hilary: “The Mediator Himself, established in Himself for the salvation of the Church, and by that very sacrament of mediation between God and men existing as one in both, since He, from the natures united into Himself, is the same reality of both natures — yet in such a way that He lacked neither in either, lest perchance God should cease to be by being born man, or man in turn should not be by remaining God.”¹⁰ And St. Ambrose: “Let us preserve the distinction between the divinity and the flesh [i.e., humanity]; one and the same Son of God speaks in both, because in Him both natures are present.”¹¹

A Note on Some Incautious Patristic Language

Not all the Fathers chose their words as carefully. A few used expressions that, taken out of context, sound Monophysite — words like “mixture” or “blending.” Tertullian speaks of Christ as “man mixed with God,”¹² and St. Cyprian says “God is mixed with man.”¹³ These are simply loosely worded attempts to convey the intimacy of the union, not endorsements of a real fusion. St. Augustine — whose orthodoxy is beyond question — gives a representative example: “Just as, in the unity of a person, soul is united to body, so that a man exists, so too, in the unity of a person, God is united to man, so that Christ exists. In that person, then, there is a mixture of soul and body; in this person, a mixture of God and man.”¹⁴ But he immediately adds a caution: “provided the hearer sets aside the ordinary experience of bodies, in which two liquids are commonly so mixed that neither retains its own integrity — although even in bodies, light mixes with air without corruption.”¹⁵ In this one passage Augustine actually offers three analogies for the Hypostatic Union: the union of body and soul, the mixing of two liquids, and the mutual interpenetration of air and light. The first two lean toward Monophysitism, since both are natural compounds in the strict sense; Augustine supplies the third — air and light entering into the most intimate union without either losing its own nature — precisely to correct that impression.

The most popular Patristic analogy was the union of body and soul — which Acacius of Constantinople (c. 480) seized on to bolster his own Monophysite errors, claiming the same kind of union that joins body and soul in man joins Godhead and manhood in Christ. But Acacius forgot that every analogy is imperfect, and that the Fathers who used this one also pointed out its important disanalogies. Four stand out: first, body and soul are strictly parts of one whole, which cannot be said of Christ’s Godhead and manhood — “There, indeed, soul and body are parts of the man; but here, neither is the flesh a part of the Word, nor the Word a part of the flesh.”¹⁶ Second, in man soul and body stand in a natural relation, each requiring the other; in Christ, the relation between Godhead and manhood is entirely supernatural. Third, in man a finite spirit is united to finite flesh; in Christ, an infinite Hypostasis is united to a finite but complete nature. Fourth, Christ as God-man is both God and man at once, whereas an ordinary man is neither body alone nor soul alone, but a synthesis of the two.

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