Throughout the history of the Church, it has struggled to reach a state of unity. A challenge that has presented itself is the teachings of heresies. Through the centuries, many different heresies have threatened the unity of the Church, one significant heresy being Nestorianism, named after its teacher Nestorious. It claims that Jesus was only human when born to Mary, denying Mary to be the Mother of God, and therefor jeopardizing the unity of the Church.
A heresy is defined as “the obstinate post-baptismal denial of some truth which must be believed with divine and Catholic faith, or it is likewise an obstinate doubt concerning the same” (CCC 2089). The teaching must involve a substantial truth dealing with God's revelation or a doctrine specifically characterized by the Church itself. A heresy is different from apostasy, the complete rejection of the Christian faith, or a schism. It must oppose examples such as the Immaculate Conception of Mary, the Trinity, the Presence of Jesus in the Eucharist, or the Resurrection of Jesus. They break the unity of the Body of Christ, and teachings among heretics can lead to division among the members of the Church. Once the Church has questioned the teachings and declared them false, and the heretics proceed in teaching, it causes confusion and broken unity throughout the Church and its members. To be a true heretic, one must refuse to be corrected, and must also be baptized. One who is not baptized, or does not know their teachings are against the Church is not a heretic. They must be an active member of the Church, who is fully aware of their false teachings and dis unifying words.
Nestorius, the bishop of Constantinople during the fifth century, was the teacher of the heresy Nestorianism. It renounced the name of Theotokos meaning “God-bearer” or “The Mother of God” to Mary, expressing that Mary only bore the human Jesus, separating Jesus into two persons. He proposed an alternative title Christotokos or “Chirst- bearer”, separating Christ into one divine and one human person. It caused confusion among the Church as to which Jesus would have died on the cross, and it goes against the Incarnation which says Jesus became fully human while remaining fully divine. Nestorius taught that Mary gave birth to Christ, but not God, focusing more on Christ’s humanity than his divinity. It focused on a low Christology, or Christ’s humanity more than his divinity. It effected the members of the Church to where it led to the denial that Jesus, who is both fully God and fully human, saved humanity from the sin of Adam at the beginning of time.
Responding to the heretic, St. Cyril of Alexandria informed Pope Celestine of his belief of Nestorius' heresy. Pope Celestine granted permission to St. Cyril to take action and inform Nestorius that unless he repudiated within ten days of acquiring the warning, he would be excommunicated from the Church. Nestorius received the information, and accused the Pope of being...