The Great Schism in the Christian Church, which occurred in 1054, was the decisive split between the Eastern Orthodox Church and the Roman Catholic Church. This schism arose from longstanding theological, political, and cultural differences, particularly concerning the authority of the Pope, the use of leavened versus unleavened bread in the Eucharist, and the Filioque controversy regarding the nature of the Holy Spirit. The mutual excommunications by the Pope and the Patriarch of Constantinople marked this formal division, which profoundly influenced the course of Christian history, leading to distinct religious practices and interpretations that continue to this day.