By the fall of Rome in 476 C.E., Christianity had weathered many storms and controversies.

This map shows the split in the Christian Church after the Great Schism of 1054.

Basilica of San Vitale [CC BY-SA 4.0], [via Wikimedia Commons]

After becoming the official religion of the empire in the 4th century C.E., Christianity immediately saw a division because of Arianism, a heresy that challenged the doctrine of the divinity of Jesus. This doctrine had some heavyweight supporters, including emperors. After nearly a century of debate and in-fighting, the church established a set understanding of doctrine at Nicaea, creating the Nicene-Constantinopolitan Creed. Despite a few more heresies, the church was relatively united. However, ripples of difference began to appear after Rome fell.

The Bishop of Rome, the pope, was seen as the head of the church, the successor of Peter, Jesus's chief apostle. In the western lands, believers viewed the pope as the official head of all Christianity. However, in the East, bishops and patriarchs were torn between honoring the pope as “primus inter pares”, or first among equals, and acceding to the whims and dictates of the Byzantine emperor. Additionally, some doctrinal differences on the Trinity began to arise, as well as differences in the liturgy, or public worship. The Roman leadership of Pope Gregory the Great in the 6th and 7th centuries placed more pressure on the leading eastern bishop, the Patriarch of Constantinople. After presenting a united front against the iconoclastic attacks of Emperor Leo Saurian and his hatred for religious images, the Eastern and Western branches of the church began to slowly slide apart once again.

The biggest barrier became language. The Western church adopted Latin, while the East used Greek and various Slavic languages. Finally, in the 1050s, the Patriarch of Constantinople began to refuse orders and accept decisions from the pope in Rome. In 1054 C.E., the pope sent a legate, a representative, to Constantinople to meet with the patriarch to patch things up. The difference in language proved too much, tempers flared, and the patriarch excommunicated the legate, the pope, and the West. (Excommunication severs a person form the life of the church, including participation in liturgy and the sacraments, essential acts needed for salvation.) In return, the legate excommunicated the patriarch and the emperor in the name of the pope. This event, the Great Schism, led to two churches, with both sides viewing themselves as the rightful church.. The western side would become known as the Roman Catholic Church, and the eastern side as the Orthodox Church.