Question

Since the standardization of Christian beliefs, which change has most affected the practice of Christianity?

the end of the Roman Empire
the emergence of new Christian churches
the inclusion of other religious beliefs
the emergence of Islam in the seventh century

Answer 1

The emergence of new Christian churches.

Reason: After beliefs were standardized (creeds, canon), the biggest long-term change in how Christianity is practiced came from major schisms and the rise of new denominations (e.g., the East–West Schism, the Protestant Reformation), which created lasting differences in worship, sacraments, church structure, language of services, and doctrine.