Cyril of Alexandria, Byzantine Fresco

An Alexandrian theologian, Cyril emphasized the unity of Christ's person in opposing the Antiochene theology of the Patriarch of Constantinople, Nestorius. In this controversy Cyril was particularly affronted by Nestorius' refusal to call Mary Theotokos, "God-bearer" or "Mother of God." Cyril's contention was that Mary was not merely Christotokos or "Christ-bearer" or "Mother of Christ," as Nestorius was willing to call her, but that Mary was rightly to be called Theotokos or "the Mother of God" in order to emphasize not only the humanity but the divinity of Christ. Cyril's enduring theme was the unity of the two natures of Christ in one person. His views anticipate the attempt to settle controversies concerning the person of Christ at the Council of Chalcedon (451).