The main issue as said is that you need some political power for a religion to do well. FEI for instance has a war between the Order of the Elders and the Church of Sartan, but very little actually happens in terms of crusades and burning temples or anything, why? Because the political powers (wisely perhaps in their situation) refuse to allow such religious war to be actually fought by members of their realm. Selene tried to do it aggressively and failed horribly in this case. We attempted to do the same in Ibladesh, again failed there unfortunately.
Although there are some positive points on religion. If you can get that power and tie important political figures to a church (and not just, hey I'm a member whoopwhoop, but actually tie them to you) then you can accomplish nice things with religion. As said, being part of a religion can get you that lordship etc.
I know for a fact it's used in more realms, although perhaps secretly.
