Throughout the history of the Church, it has struggled to achieve a state of unity. One challenge that has arisen is teachings on heresies. Over the centuries, many different heresies have threatened the unity of the Church, one of them being Nestorianism, named after its teacher Nestorious. He claims that Jesus was only human when born to Mary, denying that Mary is the Mother of God and thus endangering the unity of the Church. A heresy is defined as “the obstinate denial after baptism of a truth in which one must believe with divine and Catholic faith, or it is also an obstinate doubt about it” (CCC 2089). The teaching must involve substantial truth dealing with God's revelation or doctrine specifically characterized by the Church itself. A heresy is different from apostasy, complete rejection of the Christian faith, or schism. It must be opposed to examples like 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 members of the Church. Once the Church has questioned the teachings and declared them false, and heretics continue to teach, it causes confusion and breakdown of unity within the Church and its members. To be a true heretic, one must refuse to be corrected, and one must also be baptized. Anyone who is not baptized or who does not know that his teachings are contrary to the Church is not a heretic. They must be an active member of the Church, fully aware of their false teachings and disunifying words. Nestorius, the fifth century bishop of Constantinople, was the teacher of the Nestorian heresy...... middle of paper ...... sus, the Church was able to demolish Nestorius in contradiction to the teachings of the 'Church. Works Cited Brom, Robert H. "Tracts". The great heresies. Np, August 10, 2004. Web. April 01, 2014. .Chapman, John. “Council of Ephesus.” The Catholic Encyclopedia. Flight. 5. New York: Robert Appleton Company, 1909. April 2, 2014 “Council of Ephesus.” - Theopedia, an encyclopedia of biblical Christianity. Np, and Web. March 29, 2014. “Nestorianism.” - Theopedia, an encyclopedia of biblical Christianity. Np, and Web. April 1, 2014. .Wilhelm, Joseph. "General advice". The Catholic Encyclopedia. Flight. 4. New York: Robert Appleton Company, 1908. April 2. 2014 .