Cyril, bishop of Alexandria, in the controversy which had thus arisen, appears as the great champion of orthodoxy. But all historians agree in giving him a most unchristianlike, imperious, character. He is accused of being moved with jealousy because of the increasing power and authority of the bishop of Constantinople; and of being restless, arrogant, and unscrupulous in his ways. He was also as violent against the heretics, as Nestorius. He persecuted the Novatianists, and expelled the Jews from Alexandria. An honest and pious zeal may have animated these great prelates, but they utterly failed in uniting with their zeal Christian prudence and moderation, and too readily allied with it the worst passions of human nature.
Cyril was first drawn into the controversy by finding that copies of Nestorius' sermons had been circulated among his monks in Egypt, and that they had abandoned the term, Mother of God. He at once blamed both the monks and Nestorius, and denounced the novelty as heretical. All parties were soon excited, and angry words were used by all parties which need not now be repeated. Suffice it to say, that when Nestorius found that Cyril had skillfully managed to secure the influence of Celestine, bishop of Rome, and that he was beset with other difficulties, he appealed to a general council. As some of his opponents had already petitioned for such an assembly, it was agreed to, and the Emperor Theodosius issued orders for the meeting of one at Ephesus in the year 431, which is called the Third General Council. They met in June. Cyril, in virtue of the dignity of his see, presided. Matters went against Nestorius. He was condemned as guilty of blasphemy, deprived of the episcopal dignity, cut off from all part in the priesthood, and sent into banishment, in which he closed his days about the year 450.
About two hundred bishops signed the sentence against Nestorius; still it remains a question with most historians, whether he was really guilty of holding the errors for which he was condemned. But all are agreed that he was rash and intemperate in his language, vain of his own eloquence, disregarded the writings of the earlier Fathers, and was apt to see heresy in everything that differed from the dogmatic phraseology which he had been accustomed to in his youth. But it is difficult to determine which was the principal cause of this great contest, Cyril or Nestorius.