By that metric, that overstates growth in 3rd world countries, fundamentalist Islam and ultra-orthodox Jews are doing even better.

When I use the word "mistake" I am not referring to number of dumb followers, is about intellectual relevance. It is pretty clear that, in developed countries, these obscurantist and fundamentalist creeds are loosing cultural hegemony (e.g.: same-sex marriage, marijuana legalization, multiculturalism, abortion, etc).