Well it should make EVERYBODY curious as to why they don't speak out more vehemently. Ordinary Muslims, have a far greater and more in depth knowledge of the Koran; that the rest of us. Therefore, it follows, that if a group ( all be it an every increasing size ) purport to be carrying out the doctrines of the Koran ( by killing non believers ) that can be argued against; by their fellow moderates, that see the Koran in a different light. Islamic Extremists, are hardly going to listen to doctrinal arguments concerning their faith; from people who don't practice that faith. A great many became radicalised, by having those arguments put to them by extremists; the flip side of that, is to have the vast majority counteracting that by putting their point across in NO UNCERTAIN TERMS !!