Catholicism
Catholicism is the largest Christian Church, claiming about 1.07 billion members as of 2003.[1] Catholicism is structured into 22 distinct Churches, all of which are in communion with the Pope. Each Church within Catholicism is headed by a bishop known as a patriarch. A patriarch is responsible for ordaining new bishops and establishing new diocese. The largest of these Churches is the Roman Catholic Church, whose patriarch is the Pope, bishop of Rome.
Catholicism views itself as being in historical and doctrinal continuity with Jesus and the 12 Apostles. This expresses itself in several ways within Catholicism. Catholicism holds bishops are the successors to the apostles, and that all Catholic bishops can eventually trace their ordination back to one of the apostles (who in turn is traced back to Jesus).
Catholicism before the Schism with Eastern Orthodoxy
Before the Schism of 1066 Christianity existed as what is sometimes called "the great Church" with most Christians, apart from a few notable exceptions, living within the confines of the Roman Empire. During the third and forth centuries the Eastern and Western halves of the Roman Empire began to experience increased tension as they drifted apart culturally and linguistically. These changes would become after the barbarian invasion and the eventual collapse of the Western Roman Empire in the fifth century. The repercussions of this cultural split were felt within the religious outlooks of Eastern and Western Christians even before the 1066 schism. In what was formerly the Western Roman Empire, administrative power began to be consolidated in Rome by the Pope as most of the social services provided by the Empire began to collapse. This would lead Pope Gregory the Great to establish a bureaucratic system known as the Vatican today. While not officially part of the Roman Empire anymore, the Pope was canonically required to have his ordination approved by the Eastern Roman Emperor until the title was bestowed on Charlemagne in 800. During this period the filioque would become uniformly added to the creed in the Western Church. These two developments drove the Eastern and Western Church further apart. Eventually, in 1066, the Eastern and Western Churches severed official ties. This took place when a representative of the Pope attended the feast of St. Andrew in Byzantium. During feastal liturgy he delivered a bull (without the Vatican's knowledge) excommunicating the Eastern Church for refusing to add the filioque to the creed and ordaining married men (which the Western Church had ceased to do by this point). While the Easter Church excommunicated the Vatican's representative and not the Western Church, the two Churches had become too different in character to maintain any kind of official unity.