WELL... if we take into account all the things that come into people making decisions: brute force, good ideas, social paradigm shifts, taboos, varying concepts, etc. it seems that conversion of religious ideas (when only sometimes accepted, and not completely - as we DO have different religions out there) aren't completely understood by anyone that hears of them. In order to gain a full understanding of a religion, someone must actually participate in it. Religions can't be understood by sharing ideas, and the visible/physical transformations that happen in people when they convert or find religion or leave religion have nothing to do with ideas that "infect" people. The act of taking it on oneself to participate is the only way to come to know the religion fully.