Granted, I'm not in their heads, but IMO it's almost pure geopolitical politics to them. They want a bigger piece of the pie. They want to be seen as the preeminent power in the region (again). They want to be a player on the world stage. I doubt they really have any desire to "rid the world of infidels." More like carve out their own niche in said world instead. Not saying they are nice guys, just that their motives are familiar and, that said, gameplanable. I think what they really envision is a revived Persia, but under another name (Iran). While many here are not, they are very aware of the distinctions between themselves and their neighbors historically.