The Great Schism, which occurred in 1054, was the division between the Roman Catholic Church in the West and the Eastern Orthodox Church in the East. This split was primarily due to theological disagreements, cultural differences, and political conflicts, including disputes over papal authority and the use of icons in worship. The schism was marked by mutual excommunications between the leaders of the two churches: Pope Leo IX for the West and Patriarch Michael I Cerularius for the East. This event significantly shaped the religious landscape of Europe and led to the distinct development of Western and Eastern Christianity.