Cyril of Alexandria was the Patriarch of Alexandria from 412 to 444. He was enthroned when the city was at the height of its influence and power within the Roman Empire. Cyril wrote extensively and was a major player in the Christological controversies of the late-4th and 5th centuries. He was a central figure in the Council of Ephesus in 431, which led to the deposition of Nestorius as Patriarch of Constantinople. Cyril is counted among the Church Fathers and also as a Doctor of the Church, and his reputation within the Christian world has resulted in his titles Pillar of Faith and Seal of all the Fathers. The Nestorian bishops at their synod at the Council of Ephesus declared him a heretic, labelling him as a "monster, born and educated for the destruction of the church."

In Christianity, Christology is a branch of theology that concerns Jesus. Different denominations have different opinions on questions such as whether Jesus was human, divine, or both, and as a messiah what his role would be in the freeing of the Jewish people from foreign rulers or in the prophesied Kingdom of God, and in the salvation from what would otherwise be the consequences of sin.