Here is a quote from an article by Karen Armstrong from some years back on the nature of what she calls "militant piety" and how its rise across the religious landscape resulted in separatist and fundamentalist movements that were antithetical to religion:
During the 20th century, a militant piety erupted in almost every major world faith: in Buddhism, Sikhism, Hinduism and Confucianism, as well as in Judaism, Christianity and Islam. It is often called "fundamentalism." Its aim is to bring God and/or religion from the sidelines back to centre stage, though very few fundamentalists commit acts of violence. Coined by American Protestants who wanted a return to Christian "fundamentals," the term is unsatisfactory, not least because it suggests a backward-looking religiosity. In fact, fundamentalists are rebels who have separated themselves irrevocably and on principle from the main body of the faithful. Fundamentalist movements are nearly always the result of an internal dispute with traditional or liberal co-religionists; fundamentalists regard them as traitors who have made too many concessions to modernity. They withdraw from mainstream religious life to create separatist churches, colleges, study groups, madrasas, yeshivas and training camps. Only later, if at all, do fundamentalists turn their wrath against a foreign foe.
It is unrealistic to hope that radical Islamists will be chastened by a rebuke from "moderate" imams; they have nothing but contempt for traditional Muslims, who they see as part of the problem. Nor are extremists likely to be dismayed when told that terrorism violates the religion of Islam. We often use the word "fundamentalist" wrongly, as a synonym for "orthodox." In fact, fundamentalists are unorthodox - even anti-orthodox. They may invoke the past, but these are innovative movements that promote entirely new doctrines.
The same is true of the new emphasis on violent jihad. Until recently, no Muslim thinker had ever claimed it was the central tenet of Islam. The first to make this controversial, even heretical, claim was the Pakistani ideologue Abu Ala Mawdudi in 1939. He was well aware that this innovation could only be justified by the godless cruelty of modernity. Informed extremists today do not need to be told that their holy war is unorthodox; they already know.
The extremists believe that mainstream Muslims have failed to respond to the current crisis and are proud of their own deviance. Attempting to shift the blame to the already beleaguered Muslim community could further alienate the disaffected.
This is so well stated! The militant piety of Islam that the West is fighting is neither a return to "true" Islam nor a natural outgrowth of Islam. It is a radical and fundamental cleavage from Islam. Muslim radicals do not listen to or respect their religious leadership. They wish their destruction just as much as ours. The only authority they respect is their own. They have freely chosen separation from the community and therefore are not to be considered the mainstream or orthodox version of Islam.