I think..

[polli]

I think I have figured a way to make crusades viable but need some classification. The tactic of making peasants in say england and then disbanding them in the captured middle eastern province. Once disbanded they would join the general population and be christian to try and convert. Would this work. I cannot test myself as I am having problems with Rome so if someone could test would they please tell me.

Also why can you not destroy mosques when you capture settlement. As this would surely help to convert the pop to chrisitianity. Can Muslim factions destroy church buildings?

[DaVinci]

Exactly for the purpose of disbanding people in the Levante, i've set up the 'Settlers' (peasants) to recruiting for cheap money in homelands, in case you've slaughtered too many inhabitants. As well, it is indeed historical, that the Levante cities were boomtowns in that crusader time (especially pilgrims to Jerusalem).

The AI cannot destroy buildings, so here (undestroyable mosques) is the challenge for the player to find a way to found and keep the crusader state .. and it is possible, as you have several options.
Without all the difficulties that i coded in, the mod would be too easy as a crusading faction player, at least for me.