The author gives the terrorists too much credit. While I believe at one time they were driven by their beliefs, I think they have evolved into a group or psychopaths who joined up in order to be able to live out their destructive ambitions using religion as a cover.
What I would like to know, are "moderate" mohammedans increasingly joining the jihad squads these days? Is the Islamicist thing building steam or not? There seems to be a whole bunch of Syrians, Jordanians, Saudis, etc. flocking to Iraq to try their luck at Holy War.
If it is, then we're going to need a whole lotta bullets and we better get a head start on making them.