How did Christianity grow and develop into a powerful religion?

What's the answer

It is not a powerful religion. Currently, many Christians are not religious. Countries that used to be Christian are now secular. Christians are not serious about their religion.

Christianty was brought from spain by the spaniards. When they came to the " New World" spaniards saw indians giving belief into unholy and worshipping satan. So the soaniards rounded them up and priests forced them to worship christianity and priests would go out a round up more indians making them become like them worshiping one god and not so many then the indians would soon accept but alot wouldn't accept and those who wouldnt were killed and it soon spread through each individual.