Little is known for certain of Cyril’s early life. He was born c. 376, in the small town of Didouseya, Egypt, modern-day El-Mahalla El-Kubra. A few years after his birth, his maternal uncle Theophilus rose to the powerful position of Patriarch of Alexandria. His mother remained close to her brother and under his guidance, Cyril was well educated. His writings show his knowledge of Christian writers of his day, including Eusebius, Origen, Didymus the Blind, and writers of the Church of Alexandria. He received the formal Christian education standard for his day: he studied grammar from age twelve to fourteen (390–392), rhetoric and humanities from fifteen to twenty (393–397) and finally theology and biblical studies (398–402).
Recognized as a great teacher of the Church, Cyril began his career as archbishop of Alexandria, Egypt, with impulsive, often violent, actions. He pillaged and closed the churches of the Novatian heretics—who required those who denied the faith to be re-baptized—participated in the deposing of Saint John Chrysostom, and confiscated Jewish property, expelling the Jews from Alexandria in retaliation for their attacks on Christians.
Cyril’s importance for theology and Church history lies in his championing the cause of orthodoxy against the heresy of Nestorius, who taught that in Christ there were two persons, one human and one divine.
The controversy centered around the two natures in Christ. Nestorius, Bishop of Constantinople, would not agree to the title “Theotokos” or “God-bearer” for Mary. He preferred “Christ-bearer,” saying there are two distinct persons in Christ—divine and human—joined only by a moral union. According to Nestorius, Mary was not the mother of God but only of the man Christ, whose humanity was only a temple of God. Nestorianism implied that the humanity of Christ was a mere disguise.
Against Apollinarius, Nestorius wished to teach that Christ was a perfect man, and he took the denial of a human personality in Our Lord to imply an Apollinarian incompleteness in His Human Nature. The union of the human and the Divine natures was therefore to Nestorius an unspeakably close junction, but not a union in one hypostasis. Meanwhile St. Cyril taught the personal, or hypostatic, union in the plainest terms; and when his writings are surveyed as a whole, it becomes certain that he always held the true view, that the one Christ has two perfect and distinct natures, Divine and human. The Saint brought out the necessity of the full doctrine of the humanity to God, to explain the scheme of the redemption of man. Nestorius refused to accept such terminology, and their dispute was referred to a general council at Ephesus in 431. In the confusion that followed, Cyril was deposed and imprisoned for three months, after which he was welcomed back to Alexandria.
Cyril was a man of great courage and force of character. We can often discern that his natural vehemence was repressed and schooled, and he listened with humility to the severe admonitions of his master and advisor, St. Isidore. As a theologian, he is one of the great writers and thinkers of early times. Yet the troubles that arose out of the Council of Ephesus were due to his impulsive action; more patience and diplomacy might possibly even have prevented the vast Nestorian sect from arising at all.
Besides needing to soften some of his opposition to those who had sided with Nestorius, Cyril had difficulties with some of his own allies, who thought he had gone too far, sacrificing not only language but orthodoxy. Until his death, his policy of moderation kept his extreme partisans under control. On his deathbed, despite pressure, he refused to condemn the teacher of Nestorius.