d.444. Patriarch of Alexandria. He was probably destined early for an ecclesiastical career and perhaps learned theology among desert monks. He assisted his uncle, Patriarch Theophilus, at the Synod of the Oak* (403) and contrived to succeed him in 412. With familial bellicosity he assailed Novatianists, Jews, Origenists, and pagans, and most strenuously Nestorius of Constantinople, who heeded complaints of refugee Egyptian monks against Cyril and disapproved of designating Mary Theotokos, “God-bearer” (428-29). Cyril's vehemence against Nestorius (see Nestorianism) vented traditional Alexandrian jealousy of Constantinople as well as horror of his typically Antiochene Christology. Armed with synodal condemnations from Rome (Celestine I) and Alexandria, Cyril sent Nestorius twelve anathematisms and demanded his prompt recantation (430), and at Ephesus in 431 secured his deposition (and the canonizing of his second letter to Nestorius, but not formally his third, with the anathematisms) by initiating proceedings before the Antiochenes arrived. The emperor recognized Cyril's assembly, not the Antiochenes' (which deposed Cyril), as the general council, and exiled Nestorius.

Such extremism demanded redress. With imperial prompting and after tortuous negotiations, Cyril approved an Antiochene “Formula of Union,” John of Antioch* accepted Nestorius's excommunication, and Cyril's anathematisms quietly lapsed (433), although he campaigned still against unbudging defenders of Nestorius, especially Theodoret of Cyrrhus* (the compiler of the “Formula of Union”), and even Nestorius's old teacher, Theodore of Mopsuestia.*

Cyril's writings voluminously reveal the man-the ruthless theologian, forceful, acute, profuse, but inelegant, pompous, and myopic. Extensive exegetical works survive (allegorical commentaries on Isaiah, the Minor Prophets, and parts of the Pentateuch, more literal ones on John and Luke), plus a third of his massive reply to Julian's Against the Galileans, about twenty sermons, and many letters of dogmatic interest. Of his anti-Nestorian treatises, That Christ is One is a mature example. The early anti-Arian Treasury and Dialogues on the Holy and Consubstantial Trinity present an undeveloped Christology. Their heavy dependence on Athanasius* highlights Cyril's influential practice of arguing from “the holy Fathers.”

Against Nestorius he vindicated the “Hypostatic Union”* of divine and human in Christ which guaranteed the eucharistic reception in His divinized flesh and blood, but gave the impression, by his mistaken appeal to Apollinarian phrases (especially “the one incarnate nature of the Word”) as Athanasian, by his analogies, and by his use of physis to mean both “nature” and “person” of teaching Apollinarianism* and Monophysitism.* A major forerunner of Chalcedon (which also canonized his 433 letters to John of Antioch), Cyril nevertheless failed to develop a fully fledged appreciation of the role of Christ's humanity.

Works: J. Quasten, Patrology 3 (1960), pp. 116-42; PG 68-77; several works ed. P.E. Pusey (1868-77) and E. Schwartz, Acta Concil. Oecum I, 1-5 (1927-30).

Selected Studies: B.J. Kidd, A History of the Church to a.d. 461 (1922); R.V. Sellers, Two Ancient Christologies (1940); G.L. Prestige, Fathers and Heretics (1948); H. von Campenhausen, Fathers of the Greek Church (1963); A. Grillmeier, Christ in Christian Tradition (2nd ed., 1975); R.W. Wilken, Judaism and the Early Christian Mind: a Study of Cyril of Alexandria's Exegesis and Theology (1971).