Soo... in the year 1054, the Christian Church split into a Western Church and an Eastern Church. In this schism (or official separation) the church in the west became the Roman Catholic Church and in the east it became the Eastern Orthodox Church. Disagreements between the Western and Eastern Churches had been going on for a while now.. Most disagreements centered on the question of who had religious authority, the pope in Rome or the Byzantine emperor and the patriarchs (religious leaders of the eastern Christian church) in Constantinople. An early dispute erupted over the use of icons, or religious images. In the year 730, the Byzantine emperor, Leo III, banned the use of icons in Christian homes and churches. The pope disagreed with this and Pope Gregory III went as far as excommunicating the emperor. In 843 the ban was lifted, but the split between east and west had started to begin.
The power struggle between the pope and Byzantine emperors continued. The pope turned to political and military leaders in the west for support and began to cut ties with the Byzantine emperor. In the year 800, the pope crowned Charlemagne the new Holy Roman Emperor. This outraged the Byzantines who felt that the Byzantine emperor was the true ruler of the Roman Empire. The dispute between the pope and Byzantine emperors still remained. The pope claimed authority over the church, kings, and emperors, including the Eastern Church and the Byzantine emperor. The Byzantine emperor claimed authority over the eastern patriarch and the church in the east. This matter came to a head in 1054. Cerularius, the patriarch of Constantinople, closed churches that used western rites. Pope Leo IX was furious and sent Cardinal Humbert to Constantinople to deliver a proclamation by the pope excommunicating Cerularius. Cerularius then excommunicated the cardinal, even though he had no power to do so. These actions showed that the schism between the Western Church and Eastern Church was said and done.