The primary issue that led to the Schism in 1054 between the Eastern and Western churches centered around theological and political differences, particularly the concept of papal authority. The Western Church, led by the Pope in Rome, claimed supremacy over the Eastern Orthodox Church, which was governed collegially by bishops and patriarchs. Additionally, disputes regarding the Filioque clause in the Nicene Creed, which addressed the procession of the Holy Spirit, exacerbated tensions. These differences culminated in mutual excommunications and an enduring divide between Catholicism in the West and Orthodoxy in the East, shaping the future of Christianity.