The position I critique in this paper is really a complex of closely overlapping positions, some more theoretically sophisticated or better grounded empirically than others.1 Their central thrust is to emphasize the similarities rather than the differences between current movements in the world religions, particularly Christianity and Islam, but also to a lesser extent in Buddhism, Hinduism and Judaism. It appeals more to social scientists than to those working in religious studies, particularly scholars of specific religious traditions. It also taps into a common lay attitude to what might be called a ‘secular common sense’, which feels impatience or distaste for all forms of what it considers religious extremism, while at the same time shying away from regarding any one religion as more prone to extremism than others. This is the kind of interlocutor who will counter an observation about violent militancy in contemporary Islam – in the context, let us say, of a discussion about Boko Haram – with ‘But what about the Crusades’?