The Bible says that you can't get good fruit from a bad tree---something akin to the acorn doesn't fall far from the tree. So history is always useful for these comparisons, and to say that modern Islam bears no resemblance to the older forms is PRECISELY the point: it does, in almost every way. Islam has never changed, and that is why it is so dangerous. It is still a violent religion, and always has been.
The Mongols are surprising to me. Archers on fast horses were their main military weapon ? Seems hard to understand how that 'weapon' allowed them to conquer so much. Its entirely possible that their mindset was the main factor that allowed them to destroy Islamic forces.
When fighting Barbarians, one must use barbaric tactics. Otherwise you end up folding like Rome. I say bring out the tactical nukes.