Cyril of Alexandria

Cyril of Alexandria (c. 376–444), patriarch of Alexandria, was the chief architect of orthodox Christology. At the Council of Ephesus (431) he led the condemnation of Nestorius and the affirmation of Mary as Theotokos (“God-bearer”), insisting on the unity of Christ’s person. A formidable exegete, his Commentary on Luke survives largely in an ancient Syriac version. Later tradition called him the “Seal of the Fathers.”

Cyril's lasting contribution is Christological: against Nestorius he insisted that the one Lord Jesus Christ is a single person, truly God and truly man, so that it is right to call Mary Theotokos, God-bearer. A prodigious commentator on John, Luke, and the Old Testament, he read the whole of Scripture as testifying to the unity of Christ, and his formulas were decisive at Ephesus (431) and behind the definition of Chalcedon (451).