seriously, though... read Chinua Achebe's "Arrow of God"...

it's not uncommon that when a people are conquered, they accept the gods of their conquerors. not only because they are forced to, but obviously, if these people kicked their asses, their gods must be stronger, right?

it just seemed that the Christian God was more powerful than all local ones, and people switched over because everybody wants to be on a winning team. plus, Christianity brought with it certain "goodies" that some would describe as "modernity"... people wanted to be a part of that.