There are several theological and political factors, but primarily the authority of the Pope
The Catholic Church in the West and the Orthodox Church in the East
He hoped that the Eastern Church (Orthodox) and Western Church (Catholic) would be reunited.
In 1054 Christ's which (except for small groups of heretics and the Oriental Orthodox) was generally undivided and truly one split into the Roman Catholic Church and the Eastern Orthodox Church. The Orthodox would see the division this way: before 1054 there was just the Orthodox Church. After 1054 there was the Orthodox Church and the heretical church of the Patriarch of Rome, which would eventually call itself the Roman Catholic Church. The Romans would say that prior to 1054 there was just the Roman Catholic Church and then the Orthodox split off becoming a separate church. The way I, an Anglo Catholic, see it was that they both split from each other creating the Roman Catholic and Eastern Orthodox churches. Neither church really existed as a separate denomination before. The denominational terms came into existence because of the tragic split.
There is only one Catholic Church. There are no divisions. There are some non-Catholic denominations who call themselves Catholic but who are not Catholic, they are Protestant. If the church is not united under the pope in Rome, it is not a Catholic Church.
The Orthodox Church is considered to have originated first, with roots tracing back to the early Christian communities in the Eastern Roman Empire. The Catholic Church developed later, with the Great Schism in 1054 leading to the split between the Eastern Orthodox Church and the Roman Catholic Church.
diocese
The changing times.
The excommunications of 1054 led to the Great Schism between the Roman Catholic Church and the Eastern Orthodox Church. This division created a lasting rift between the two branches of Christianity that persists to this day.
The Catholic Church and The Orthodox Church are divided, primarily, over the role of the Bishop of Rome (the pope) as the authoritative successor of St. Peter. Within The Catholic Church, proper, there is the Latin Rite and the Eastern Rite. There is no theological division between these two rites within The Catholic Church.
The Council of Trent failed to reunite the Catholic Church with the Protestant movement. Despite efforts to address some of the issues raised by the Protestant Reformation, the council ultimately solidified the division between Catholics and Protestants.
According to my textbook "world religions western traditions" contentions between the doctrine of whom Christ was, was prominent between the two sects ultimately leading to a power struggle between the East and the West. Division also probably had to do more with politics and cultural differences. Characteristics that varied from Latin Christianity which was prominent in Orthodox Christianity was the fact that Latin wasn't the only language which liturgy took place in, the marriage of clergymen was acceptable, and they didn't see the pope as the head of the church.
The Old and New Testaments.