In the 7th and 8th cent. the Eastern Church lost to Islam all Asia except Asia Minor. Alienation from the West was exacerbated by the bitter struggle over iconoclasm; ecclesiastical animosity between Rome and Constantinople came to a head in the schism of the 9th cent. This schism centered on the addition of the Filioque to the Nicene Creed (see creed) in the West and on the western church's use of unleavened bread in the celebration of the mass and insistence on clerical celibacy. The division between East and West grew wider and attained a sort of legal permanence in 1054 (see Leo IX, Saint). Eastern and Western Christendom were already in the 9th cent. two different cultures; their one common tie was the Christian doctrine—even worship and practices were very different. From this time it is customary to distinguish Christian history in its Eastern and Western streams as that of the Orthodox Eastern Church and Roman Catholic Church.