St. Cyril of Alexandria was born in AD 370, was ordained a priest, and lived a monastic life until he succeeded his uncle as patriarch archbishop of Alexandria, Egypt in 412. In 431 he presided over the Ecumenical Council of Ephesus which opposed the teaching of Nestorius and defined the inseparable unity of the divine and human natures of Christ, and thus the appropriateness of invoking the Blessed Virgin Mary under the title of “Theotokos” or Mother of God. He died in 444. And is revered by Catholics, Eastern Orthodox, and Coptic churches as one of the greatest of the Fathers of the Church. Roman Catholics also recognize him as a Doctor of the Church.