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Introduction

After Constantine the Great, the Roman Empire began to break apart. Barbarian invasions hastened the eventual division of the empire into eastern and western halves. This division affected the church. Education declined and fewer scholars were able to understand both Greek and Latin. This led to misunderstandings within the church. The popes made claims that rankled eastern leaders. The western church, without consulting the eastern patriarchs, added a clause to the Nicene Creed declaring that the Holy Spirit proceeded from the Son as well as the Father. In 1052 Latin Christians forced Greeks in Italy to use western forms of worship. Patriarch Cerularius of Constantinople retaliated by demanding that Latins in Constantinople use eastern forms. When they resisted he closed their churches. Pope Leo IX sent a delegation headed by Cardinal Humbert to resolve the issue. Both Humbert and Cerularius were stubborn men and could not reach agreement. Meanwhile Leo died, invalidating Humbert’s credentials. Although Humbert was aware of this, on this day, 16 July 1054, he placed a letter of excommunication on the altar of the great Hagia Sophia cathedral. As Humbert and his fellow delegates marched out Humbert said,