it would be cool if the player could choose to convert his faction to heresy from catholic. there would need to be a new line of buildings ("heretic lodges") where the state-sponsered heresy is taught to the people, and heretics are recruited. heretics should get the ability to subvert priests and an uber-class of heresiarch created.

even if this is not possible, could it be possible to mod the game so that factions could convert to islam or orthodox?