One of the most depressing realities of modern life is the regularity with which deadly attacks are carried out in the name of Islam. Almost as depressing are the invariable reassurances by Western political leaders and media elites that these acts of violence had "nothing to do with Islam." As part of these reassurances we will also regularly hear the terms Radical Islam, Islamism, Militant Islam, 'so-called' Islamic State (ISIS) and Jihadist bandied about as if people who act violently on behalf of Islam are somehow perverting the pristine teachings of the Muslim religion. Yet, niggling...