I have to agree with loren. Religion in the game exists, as far as I'm concerned, as another avenue for spurring conflict and war. What more perfect reason could there be for war than to purge the world of some false religon (I.e. every other religion than your own) that keeps trying to convert your followers to their evil ways?
It does take people willing to go along with religion before it can work, though. IMO, it is up to the leaders of the religion to make their faith attractive to the regular players.
You can claim they are all heathens deserving death without having to bother being a priest, or even being involved in a religion at all.
IMO, the best religion would be one that has many noble followers and no temple. The priest game is a distraction, it makes you focus on follower counts and infrastructure maintenance instead of on influencing other characters.
