Within nearly the first 100 years of its practice, Nicene Christianity called to convene three separate Ecumenical Councils. The first was the First Council of Nicaea that set out the initial foundation of the Nicene Creed and established that the Father and the Son were one and the same, as well as denouncing Arianism, which challenged this notion. Despite this, the First Council of Constantinople that convened nearly 60 years later, was required to address the relationship of the Holy Spirit to complete the Holy Trinity. It also checked balances of power within the church’s structure, and some maintain that its aftermath began to show wear between the influence of the West on the East as Constantinople became a seat of considerable influence. By the year AD 431, a third Ecumenical Council was called by Emperor Theodosius II, the Council of Ephesus, to address conflicting beliefs and teachings of Nestorius, who maintained that the Virgin Mary could be called the “Birth Giver of Christ” (or Christotokos), but not the “Birth Giver of God” (Theotokos). These beliefs would be aptly identified as Nestorianism.
Nestorius’ teachings were predominantly founded on the belief of the separation of Christ’s natures as both human and divine, and thus maintained that the Virgin Mary should not be addressed as Theotokos. These beliefs and his position as Patriarch of Constantinople brought him at odds with the Patriarch of Alexandria, Cyril. Due to their conflict, Cyril addressed the pope at the time, Pope Celestine I, to intervene on Cyril’s behalf. Pope Celestine came to favor Cyril’s position and informed the Patriarch of Alexandria to request that Nestorius recant his position or face excommunication from the church.
In an effort to maintain his position as well as his beliefs, Nestorius himself approached Emperor Theodosius II to call for the convening of an Ecumenical Council so as to support the validity of his teachings and override the decree of Pope Celestine. His opponents believed that he detached Christ’s divinity from his humanity and thus denied the nature of Christ is consubstantial with the Father as well as one with man. Nestorius believed that Christ could not be both, as it would be contradictory. To be even partially man would imply that Christ was capable of aging and dying, as well as fallible in sin. The implication of Nestorius’ teachings, as interpreted by his opponents, was that Christ was separated into two distinct beings: one human and one divine, and thus denying the title of Theotokos to the Virgin Mary.
Emperor Theodosius II called for the convening. The council lasted over the course of several weeks as bishops congregated to Ephesus in stages, holding informal discussions of the matter at hand. Near the end of July, AD 431, the convened Council had denounced Nestorius’ teachings, asserting that Jesus was indeed one being that was both human and divine in nature. Several minor canons were also passed through the course of the council’s congregation, though the greatest legislation to come out of the Council of Ephesus was the outlawing of bringing forth rival Faiths to challenge that which was established through the Nicene Creed. As a result, those who followed the teachings of Nestorius found themselves on the other side of a schism that occurred between Nestorianism and Nicene Christianity. These differences would eventually be reconciled as factions acquiesced to the condemnation of Nestorius. However, it would not be the last time in history that Nicene Christianity faced upheaval.