What were two of the reasons for the Great Schism?

The Great Schism came about due to a complex mix of religious disagreements and political conflicts. One of the many religious disagreements between the western (Roman) and eastern (Byzantine) branches of the church had to do with whether or not it was acceptable to use unleavened bread for the sacrament of communion.

Causes of the schism included political, cultural, economic, and social as well as theological differences that originated before 1000. The political unity of the Mediterranean world was shaken and finally destroyed through the barbarian invasions in the West and the rise of Islam in the East.