What's a similarity between the roles of Post-Classical Christianity and Islam?

The correct answer is B) Both religions experienced a decline in popularity because of widespread persecution.

The other options of the question were A) Both religions blended together to form a distinct new faith. C) Both religions quickly expanded and became stabilizing forces in their regions.

D) Both religions conquered new territory but did not allow conquered peoples to convert.

A similarity between the roles of Post-Classical Christianity and Islam was that both religions experienced a decline in popularity because of widespread persecution.

Christianity spread from the Middle East to Western Europe and the Roman Empire adopted this form of religion during Constantine rule. But during the post-classical era, a time of conflicts in this region of the world, invasions and change of powers meant persecution of Christians and Muslims by invaders that oftentimes professed pagan beliefs. We are talking about the time than ran from approximately 1200 to 1450 CE.