The Islamic State’s ideology exerts powerful sway over a certain subset of the population. Life’s hypocrisies and inconsistencies vanish in its face. Musa Cerantonio and the Salafis I met in London are unstumpable: no question I posed left them stuttering. They lectured me garrulously and, if one accepts their premises, convincingly. To call them un-Islamic appears, to me, to invite them into an argument that they would win. If they had been froth-spewing maniacs, I might be able to predict that their movement would burn out as the psychopaths detonated themselves or became drone-splats, one by one. But these men spoke with an academic precision that put me in mind of a good graduate seminar. I even enjoyed their company, and that frightened me as much as anything else

In reviewing Mein Kampf in March 1940, George Orwell confessed that he had “never been able to dislike Hitler”; something about the man projected an underdog quality, even when his goals were cowardly or loathsome. “If he were killing a mouse he would know how to make it seem like a dragon.” The Islamic State’s partisans have much the same allure. They believe that they are personally involved in struggles beyond their own lives, and that merely to be swept up in the drama, on the side of righteousness, is a privilege and a pleasure—especially when it is also a burden.