The title of Theotokos, attributed to Mary, appears in the writings of Alexander of Alexandria in 325, the year the Council of Nicaea, then, long before that of Ephesus in 431, it is very common. In the Latin Church, the title of Mother of God is sometimes made by deipare.
History of the name Theotokos.
Jesus Christ, only Son of God, true God from true God, the Holy Spirit he became incarnate from the Virgin Mary and became man. This is what these words proclaimed the symbol faith statement by the Council of Constantinople in 381. Of course, Christians have become accustomed to give Mary the title Mother of God.
This title gives rise to a controversy between the theologian Nestorius, patriarch of Constantinople, who emphasizes the distinction between divinity and humanity in Jesus, he goes to war against what he sees as a new heresy: I refuse to see a God formed in the womb of a woman! For him, Mary is the mother of the man Jesus, not the eternal Word. The dispute is profound because it also affects the dogma of the divinity of Jesus. Two camps, the supporters of the title Theotokos and the supporters of Anthropotokos. Initially proposed the title of Nestorius Christotokos to reconcile the two camps and resolve a dispute which agitated the Church.
His attacks against the title of Mother of God face to Cyril, bishop of Alexandria, a great defender of the unity of Christ God and man. What is at stake is not the status of Mary, but the reality of the Incarnation, Jesus son of Mary is really God? If so, his mother can truly be called Mother of God. Refuse the title of Theotokos to Mary would thus separating the divinity of Jesus’ humanity, or to admit the divinity of Jesus after his design, which then join the Arian heresy. The charge of Arianism could also turn against supporters of the title Theotokos, as an affirmation of the separation of the two natures of Christ, divine and human, while the Nicene Creed said in perfect union. The controversy is therefore important and delicate. Add to this popular fervor, away from sharp theological disputes, in favor of the title Theotokos.
Cyril is no expense, wrote to the monks of Egypt, to the bishops, the pope of Rome to Nestorius himself. After many adventures, exchanges of letters and memoirs theological, an ecumenical council held at Ephesus in 431, Marian city par excellence: it is here that Mary would have lived with John after Pentecost. Hundred and fifty bishops from East and West spend the recognition by the Church of Mary’s divine motherhood.
Popular piety was immediately endorsed this statement by theologians: Holy Mary, Mother of God, pray for us. You truly Theotokos, we magnify you.