Christianity became the official religion of the Roman Empire after AD 313. The growing division between the Eastern and Western Empires was reflected in the religious schisms that developed in subsequent centuries.
Major issues about the nature of Christ and the Holy Ghost were hotly debated, sometimes to the death, and many different sects arose. The western church, under the spiritual leadership of the Pope in Rome, established Catholic orthodoxy. In the east, the seeds of the Greek Orthodox church were developing.
Other sects also enjoyed considerable support for long periods. Barbarian peoples coming under Roman influence were often converted to whatever sect they happened first to encounter.
This had far-reaching consequences. The Goths and Vandals became converts to what became known as the Arian Heresy. When they became rulers of lands within the Western Roman Empire, their Arian beliefs were a barrier to their integration with their Catholic subjects. The Franks, on the other hand, were Catholic converts and had no such problems.
