|Assembly of the Third Ecumenical Council at Ephesus for trying Nestor, Archbishop of Constantinople|
On this day in the year 431 A.D. the third Ecumenical Council at Ephesus was assembled and was attended by two hundred bishops. That was in the 24th year of the reign of the Roman Emperor Theodosius the Junior, the son of Arcadius, the son of Theodosius the Great.
They assembled because of the heresy of Nestor the Archbishop of Constantinople. He believed that St. Mary did not give birth to the Incarnated God, but only to a man, and that afterwards the Son of God dwelt in him, not the dwelling of unity but the dwelling of desire and will only, and therefore, Christ had two natures and two wills.
The assembled fathers debated with Nestor and proved to him that He Who was born of the Virgin was the Incarnated God, as the Angel announced to her: "Behold, you will conceive in your womb and bring forth a Son, and shall call His name Jesus. He will be great, and will be called the Son of the Highest" (Luke 1:31, 32). Isaiah also said: "Behold, the virgin shall conceive and bear a Son, and shall call His name Immanuel (Isaiah 7:14) and "His name will be called wonderful, Counsellor, Mighty God, everlasting Father, Prince of Peace" (Isaiah 9:6).
St. Cyril the 24th Pope of Alexandria, who was present explained to Nestor that "Natures cannot be separated after they have united. We say that the Word of God which became man has one nature only". Nestor would not turn from his teaching nor change his mind. St. Cyril with the whole Council threatened to excommunicate him but he was adamant. So they excommunicated him and removed him from his chair.
They then moved that the Virgin Mary had given birth to the Incarnated Word and they called her "The Theotocos" or "The Mother of God." They drew up Canons for the believers which are with us till this day.