Cyrrhus’s refutations of his anathemata with Against the Eastern Bishops and the Letter to Euoptius. While in prison after the council, he wrote the Explanation of the 12 Anathemata on the same subject. From the outset he understood the importance of having the emperor, or at least some members of the imperial family and the court, on his side: this explains the three texts On the True Faith, the first addressed to Theodosius II, the second and third to the emperor’s wife and sisters, in 430. After his return to Egypt came the Defense to the Emperor, in which he justified his actions before and during the council.
The post-431 Scholia de incarnatione unigeniti, in which Cyril clarified the mode of union of the two natures in Christ, without confusion but also without division, survive entirely only in Latin translation. We have only extracts, albeit copious ones, of Against Diodore and Theodore, written ca. 438 as part of the campaign unleashed by implacable antiNestorians against these two great Antiochene doctors, accused of having anticipated Nestorius’s divisionist Christology. We should also note Against Those Who Will Not Admit That the Holy Virgin Is Mother of God and Christ Is One, and, among the many letters dedicated to the controversy and its aftermath, Ep. 39, to John of Antioch, in which Cyril rejoices over the reconciliation of 433, Ep. 45 and 46 to Succensus and Ep. 40 to Acacius of Melitene, in which he defends his Christology against its critics, insisting particularly on Christ’s unity of nature. The spirit that animates Cyrillian Christology is that of the logossarx approach, traditional to Alexandria from the last decades of the 3rd c. Though Cyril, after the condemnation of that christological approach in the person of Apollinaris, was very careful to bring out the integrity soul and body of the Logos’s human nature, he saw the union essentially in terms of the preeminence of the divine nature over the human nature, which is only a passive instrument of it.
So Cyril is at the other extreme from Antiochene Christology, which valued the autonomy of Christ’s human nature to the point of making it a second subject alongside the divine Logos: for Cyril this meant dividing Christ. So he heavily stressed the unity of subject in the union, in the sense that there is only one hypostasis “person”, that of the Logos, which has assumed a whole and complete humanity. Cyril was always loath, with some exceptions, to define the humanity assumed by Christ as a nature. Indeed, Cyril gradually became more and more diffident toward the traditional terminology of homo assumptus, which spoke of assumed humanity, in which the divine Logos was clothed, since it seemed to him to present the union in too extrinsic a form; he preferred to speak, with Jn 1:14, of the Logos which became man. With even greater reason, he rejected certain typical Antiochene expressions which presented Christ’s body as the temple in which the deity had made its dwelling.
Cyril always clearly specified that, in the union, the characteristics idiomata of humanity and divinity were not confused, though, by virtue of the union, we can predicate of one what is proper to the other, i.e., we can say that God suffered and died, when, properly speaking, only his humanity died communicatio idiomatum. He repeatedly put forward the example of the union of soul and body in humanity as an example in some way suitable for describing the union of humanity and divinity in Christ. But his terminology was not always consistent, partly because of political requirements: he sometimes spoke of two natures in Christ, divine and human, but his preferred terminology, esp. after 433, was that of a single nature resulting from the union, which he defined as “union of nature, natural union” Anat. 3. Accustomed to appealing widely to earlier theologians, esp. to Athanasius, to support his statements, he summed up his thought in the formula: “A single nature of the incarnate Logos,” which he believed to be Athanasius’s when in fact it was Apollinaris’s.
He admits that we must speak of two natures, but only before the union, i.e., only theoretically, since, at the moment of union, the resulting nature is only one, that of the incarnate Logos, in which the characteristics, whole and unconfused, of humanity and divinity subsist united in a single subject. Cyril was in fact the father of monophysite Christology, and it was with good reason that the monophysites went back to him as to the supreme authority.