The “extremist” thing happens in Islam periodically. It is not a one time thing. It happens when some portion of the Islamic world becomes powerful enough and has enough resources(the spice trade, booty from conquered cities, oil wealth) and time on its hands to dream of Islamizing all the world in a generation. The Koran tells them that it is required of them to convert, subjugate or kill all who are not Mohammedans. When the Jihad is stopped decisively with great destruction, it does not end. It sort of goes into remission for a time, Moslem culture becomes lethargic, but it will be back. It will always be back so long as there are Mohammedans alive. It is inherent in the Koran and the Sayings and the Biography. Mohammedans are more fatalistic than any other large group in the world. Their own deaths do not concern them in the least. It is Allah’s Will. Putting a temporary halt to Jihad absolutely requires that Jihad suffer a defeat so destructive and complete as to convince diehards that Allah does not will Islam to prevail in the current generation. Poitiers and Vienna and Lepanto were such defeats. They do not come at us now in great armies as in the past, not yet, so the nature of the defeat they must suffer is not the same but is more difficult to inflict, must be more general, and is just as necessary.