Oh, and I forgot one important point -- that playing up this "Muslim Threat" has been politically expedient for a number of politicians around the world (and definitely in the US). There's a different between the truth and the "truthiness" that gets demagogues what they want.
And as far as whipping some young men up (especially when they're cut off from women due to cultural prohibitions) into a passionate violent movement, that's been going on forever, all over the world, and the leaders (almost always older men) get their own demagoguery benefits, both psychological, power, and fiduciary. And getting a population angry at an outside enemy is a fantastic way to distract them from domestic problems. And I don't think some of the guys in the metal detector or 9mm automatic ammunition businesses (or Halliburton) mind it too much either. Not to at all say they incite it, but I don't know how strong their motivation to see it go away would be. If there's no political motivation, then they just become gangs or skinheads or whatever. I think there's too much focus on trying to uncover the rationale rather than trying to measure the testosterone level. A bull elephant during their "heat" with high testosterone levels is predisposed to attack and dangerous to be around.
