The Third Ecumenical Council, also known as the Council of Ephesus, took place in 431 AD. It was convened to address the teachings of Nestorius, the Patriarch of Constantinople, who proposed that there were two separate persons in the Incarnation of Jesus Christ. The council affirmed the unity of Christ's divine and human natures and condemned Nestorius's views as heretical. The council also declared Mary as Theotokos, meaning "God-bearer" or "Mother of God," emphasizing her role in the Incarnation. This decision reinforced the belief in the divine nature of Christ and solidified the position of the Eastern Orthodox Church on this matter.