St. Cyril of Alexandria

St. Cyril of Alexandria was born around 376 and died on 27 June 444 at Alexandria, Egypt, where he served as patriarch. A forceful and learned churchman, he became the great defender of orthodox teaching on the person of Christ against Nestorius, the patriarch of Constantinople, who taught in a way that seemed to divide Christ into two persons and objected to calling Mary the 'Mother of God.'

Cyril insisted that the one Christ is truly God made man, and therefore that Mary rightly bears the title Theotokos ('God-bearer' or 'Mother of God') — not because she is the source of Christ's divinity, but because the child she bore is truly God. He led the Council of Ephesus in 431, which condemned Nestorianism and solemnly affirmed this teaching, a foundation of Catholic Christology and Marian doctrine. A prolific theologian and biblical commentator, he is honored as a Father and, since 1883, a Doctor of the Church.