Saint Cyril of Alexandria’s Christology is not terribly complicated. He taught that the person of God the Word assumed human essence, so that after this assumption (the incarnation) He had both a divine and human essence. Sometimes essence is called “substance” as it is in the Latin tradition and other times it is called “nature” or even “hypostasis” (the latter was used by Nicea to mean essence in a non-particular sense).

The Council of Chalcedon taught that the one person of God has both a human and divine nature after the incarnation, nature being used in an essential/substantial sense. Conceptually, two main heresies denied the Cyrillian and Chalcedonian doctrines. As covered in The Political Subterfuge of Chalcedon (in the “The Doctrinal ‘Factions’” section), Nestorianism taught adoptionism and explicitly delineated that Christ was literally two people (a divine person and a human person) who were referred to as one according to honor. Eutychianism taught the exact opposite, that Christ is one person, but after the incarnation He had only a singular essence which is not specifically human in any way as He is (allegedly) not consububstantial with His own mother (Mary, the Theotokos).

Where the rubber meets the road in the preceding is whether:

  • Christ is a singular person, and
  • The singular person of Christ has both a human and a divine essence, which are mutually exclusive, after the incarnation.

As follows are proofs that Cyril adhered to both of the preceding bullet points. They were compiled by a seminary graduate who prefers to remain anonymous. These bullet points are the condensed version of Dyophysite dogma as explicitly elucidated in Chalcedon.

1. Letter 46: Second Letter to Succensus (Source: St. Cyril of Alexandria, Epistle 44, vol. 76 of The Fathers of the Church, trans. John I. McEnerney, 201-202)

I said, in stating that he [Christ] was made flesh there is a clear and unambiguous confession that he became man, nothing any longer hinders the meaning that, since he is the one and only Son and Christ, he is God and man and just as he is perfect in divinity so also is he in his humanity…the only–begotten Son of God in so far as he is known to be and is God did not endure the sufferings of the body in his own [divine] nature but suffered rather in his earthly nature.

The preceding is a transparent admission of Christ having both a divine and human nature after the incarnation.

2. Letter to John of Antioch

[T]here became a union of two natures. Wherefore we confess one Christ, one Son, one Lord. According to this understanding of this unmixed union, we confess the holy Virgin to be Mother of God; because God the Word was incarnate and became Man, and from this conception he united the temple taken from her with himself. For we know the theologians make some things of the Evangelical and Apostolic teaching about the Lord common as pertaining to the one person, and other things they divide as to the two natures, and attribute the worthy ones to God on account of the Divinity of Christ, and the lowly ones on account of his humanity.

In short, Cyril admits “the theologians” can rightly speak of “the one person” of Christ “divide[d] as to the two natures.” Being that they are differentiated post-incarnation, “the lowly ones on account of His humanity,” such as His suffering (referenced in the Second Letter to Succensus), this definitively proves that Christ can be spoken of being having two natures after the incarnation. This is the very issue Eutyches, Dioscorus, and the latter’s spiritual successors refuse to confess.

3. Letter 44: To Eulogius (made in response to critics of the preceding letter; McEnerney, 186-188)

Some attack the exposition of faith which those from the East have made and ask, “For what reason did the Bishop of Alexandria endure or even praise those who say that there are two natures?” (Διὰ τἰ δὐο φύσεις ὀνομαζόντων αύτῶν ἠνέσχετο, ἢ καὶ ἐπῄνεσε ὁ τῆς Ἀλεχανδρείας). Those who hold the same teachings as Nestorius say that he thinks the same thing too, snatching to their side those who do not understand precision. But it is necessary to say the following to those who are accusing me, namely, that it is not necessary to flee and avoid everything which heretics say, for they confess many of the things which we confess. For example, when the Arians say that the Father is the creator and Lord of all, does it follow that we avoid such confessions? Thus, also is the case of Nestorius even if he says there are two natures signifying the difference of the flesh and the Word of God, for the nature of the Word is one nature and the nature of the flesh is another, but Nestorius does not any longer confess the union as we do…It is possible to say something such as this about any ordinary man, for he is of different natures, both of the body, I say, and of the soul. Both reason and speculation know the difference, (Καὶ ὁ μὲν λόγος, καὶ ἡ θεωρία οῖδε τὴν διαφοράν) but when combined then we get one human physis [nature]. Hence knowing the difference of the natures is not cutting the one Christ into two… Because in his [Apollinarius’] time some were contending and saying that God the Word from his own nature fashioned a body for himself, he stoutly insisted to and from that his body was not consubstantial to the Word. But if it not consubstantial, then there is one nature and a completely other nature from which two the one and only Son is known to be…If, then, we speak of a union we are confessing a union of flesh animated with a rational soul and the Word, and those who speak of two natures are thinking thus also…there is one Son, and his physis [nature] is one as the Word made flesh. The bishops from the east confess these doctrines, even though they are somewhat obscure concerning the expression. For since they confess that the only begotten Word begotten of God the Father was himself also begotten of a woman according to flesh, that the Holy virgin is the Mother of God, that his person is one, and that there are not two sons, or two Christ’s, but one, how do they agree with the teachings of Nestorius?…[T]hey [the easterners] separate them [the natures] in this manner. Some are proper to his divinity, others are human, and others have a position in common as being both proper to his divinity and his humanity. Yet they are sayings concerning him, one and the same.

This prooftext is important because Cyril acknowledges the conceptual difference between himself and Nestorius, and a conceptual agreement between himself and the Antiochenes. It is not the acknowledgement of two natures in Christ after the incarnation that is the problem. Rather, its Nestorius’ failure to confess a literal, singular individual in whom these two natures exist. Cyril then makes an illustration of the human nature itself being comprised of two existing, concrete, natures. Neither undo the oneness of the overall entity. This is precisely the Chalcedonian doctrine. Cyril confesses Christ’s consubstantiality with humanity—something Eutyches explicitly refused to do without duress. The Council of Ephesus 2 tacitly rejected Cyril on this point when they defended Eutyches. Lastly, Cyril again makes clear that the differences in natures in the one person of Christ are after the incarnation, as some pertain specifically to His existing humanity.

4. Letter 45: First Letter to Succensus (Ibid., 190-193)

[H]e [Diodore] thought and he wrote that there is one son separately begotten of the seed of David from the Holy Virgin, the Mother of God, and again another Son begotten separately, the Word of God the Father…Nestorius became the disciple of this Diodore, and then with mind darkened by this books he pretends to confess one Christ, Son and Lord, but he himself also divides the one into two, saying that the undivided man was connected to God the Word by the same name, by the same honor, and by dignity. And so he separates the sayings made about Christ in the evangelical and apostolic proclamations and says that some ought to be attributed to the man, obviously the statements proper to the humanity, and others alone are suited to God the Word, obviously those proper to divinity…when we [Cyril and his supporters] assert the union of the Word of God the Father to his holy body…we confess one Christ, Son and Lord, the Word of God the Father, the same God and man, not one and another, but one and the same, being, and known to be God and man. Therefore, sometimes he speaks as man according to the dispensation and according to his humanity, and sometimes as God he makes statements by the authority of his divinity…therefore, as I said, the manner of his Incarnation we see that his two natures came together with each other in an indissoluble union, without blending and without change, for his flesh is flesh and not divinity, even though his flesh became the flesh of God, and likewise the Word also is God and not flesh, even though he made the flesh his own according to the dispensation. Therefore, whenever we have these thoughts in no way do we harm the joining into a unity by saying that he was of two natures, but after the union we do not separate the natures from one another…there are two natures which are united, but that Christ the Son and Lord is one, the Word of God the Father made man and incarnate.

Here, Cyril conceptually differentiates between Nestorianism and Orthodox doctrine. Diodore and Nestorius speak of two natures, but as applying two mutually exclusive people. Cyril allows for the speaking of two natures provided it is specific to one individual, the incarnate Word of God. It is this concept that informs Cyril’s expression “after the union we do not separate the natures.” The natural element of flesh is not divine, and vice versa. The union of natures comprises not of the combining of different essences, but of a single person having two mutually exclusive essences/natures—the Chalcedonian doctrine. Perhaps more can be said about the present tense being used in the statement that in Christ “there are two natures which are united,” but I will leave it to those with recourse to the Greek to expound upon this.

Conclusion. As my previous research has shown, the Non-Chalcedonian schism was initiated over reasons that had nothing to do with Chalcedonian doctrine. Dioscorus had confessed the same doctrine privately and his partisans had in fact drafted the Chalcedonian definition. The preceding should be of no surprise, as Cyril of Alexandria’s memory loomed large over the council and he in his own words, as the above shows, affirms dyophysite Christology. It is tragic that the Non-Chalcedonian schism persists today, allegedly in defense of Cyril, but being in fact radically separated from his explicit understanding of Christ’s natures after the incarnation.