Which was a disagreement between the Catholic Church and the Eastern

Orthodox Church?

The Catholic Church and the Eastern Orthodox Church have been in a state of official schism from one another since the East-West Schism of 1054. This schism was caused by historical and language differences, and the ensuing theological differences between the Western and Eastern churches.

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. The west supported the practice, while the east did not.