I have made comments like this before, so forgive me, but I have been studying religious fundamentalists for quite a few years. The recent brutal beheading of journalist James Foley shows one characteristic of radical fundamentalists of all religions: They don’t care what a person who is an Outsider might have done or what he or she supported. James Foley had done nothing. Rather all they care about is who he “is”. In this case, an American. The chilling corollary of this is that there is now a worldwide ideology that gives perhaps a few million dislocated young Muslim men (only a tiny percentage of all Sunni Muslims) a rationale for venting their rage indiscriminately and with righteous justification on all outsiders — all who are not members of the tribe of true believers into which they have retreated in their escape back to a reconstituted delusional world of 7th Century greatness. Feeling humiliated by the failure of their own cultures to be inventors of the powerful new world or indeed to be really successful in modernity on their own terms. they have experienced instead that success in the modern world requires becoming pale derivatives of the West. Coming from a proud past, and wanting their own identity, this is galling to them. Feeling both humiliated by cultural failures to be “great” anymore and by feeling derivative if they seek “modern” success, these factors combine to deeply enrage them. This rage is so all-consuming that it seeks no specific target, but rather seeks to lash out at the entire outside world. (Yes. They will target those whose presence and success is especially humiliating,like America and Israel.) The radical Islamist ideology gives them a long-sought rationale for venting rage against all who are not them. So they slaughter all others — Secular Sunnis, Christians, French, Americans, Brits, Jews, Israelis, etc., and their ancient enemies the Shiites too, and feel entirely justified.
Radical Islamists are present in numbers (even if small percentages) in every Muslim country (or Muslim area of other countries such as in the Sahel) and in numbers in every Western country. Thanks to social media, though dispersed they can function as a singular force. Not since the Nazis have we seen anything so terrifying or of this scale.