The term East-West Schism is a term related to the history of Christianity. Some people use the term Great Schism in place of East-West Schism. To understand the meaning of East-West Schism, it is useful to understand the meaning of schism. In very simple words, when differences arise among one group of persons or organizations and they divide themselves into two or more groups, this is schism. The term East-West Schism describes the division which happened in Christianity. The Christian church became divided into two major groups: Roman Catholicism and Eastern Orthodoxy. Most people accept that it happened in 1054. However, this separation was the result of differences that had begun many years before. One difference was the "filioque clause" in the Nicene Creed. This stated that the Holy Spirit came from the Father and the Son, although the original creed declared that It came from just the Father. One major reason for the division concerned the authority of the pope. The Eastern Orthodox group was of the opinion that the pope’s authority over them was only honorary, and the pope had real authority only over the western Christians. However instances of open division on doctrinal questions as well as daily matters had occurred long before the Great Schism of 1054. Leading up to the schism, Pope Leo IX (1002-1054) sent forth a party lead by Cardinal Humbert of Silva Candida to talk through the obvious problems between the papacy and Constantinople. Michael Cerularius, the Patriarch of Constantinople, rejected the claims put forward by the papal committee. Those from the western side of the church accused Constantinople of having altered the Nicene Creed, and those from the eastern side accused the western church of altering the creed. This in turn led to Cardinal Humbert putting forward a Bull of Excommunication against Michael Cerularius on the altar of the Hagia Sophia, and the Great Schism became official.