Originally posted by BarristerBoy
I like your other ideas, but not this one. I can't think of a single historical example where a Catholic was force-converted to Orthodox, or vice-versa. On the other hand, it definitely should be in with respect to pagans and heretics.
Vlad the Impaler converted to Catholicism in order to get Hungarian help.
However, I'm uncomfortable with this idea since I think that it'll lead to far too frequent exploitation. Perhaps it'll work if we make it something that can be offered by the defeated power, but can't be imposed by the victor? Then, limit the chances that your king will accept your suggestion that you make the change based upon his piety/personality traits. (John Lackland, sure, Louis the Pious, no way.)
Alexandre