The Great Schism of 1054 caused the split between the Eastern Orthodox and Roman Catholic Churches, marking a significant theological and political divide in Christianity. Key issues included disputes over papal authority, the wording of the Nicene Creed, and cultural differences between the Latin West and the Greek East. The mutual excommunications by Pope Leo IX and Patriarch Michael I represented the culmination of longstanding tensions and disagreements. This schism profoundly affected the development of Christianity, leading to the establishment of two distinct branches of faith that continue to influence religious, cultural, and political dynamics to this day.