Since the early years of the 21st century, the causes of war and of acts of terrorism have been strongly identified in the public mind with religion, and especially with the Muslim faith. This identification is in some ways unsurprising, but it relies upon a number of different but mutually reinforcing and long-standing cultural presuppositions. One is that religion itself has an inherent, distinctive, possibly unique tendency to promote violent acts; another is that, whatever about that, many past and present wars and terrorist acts were in fact wholly caused by specific religious commitments; another is that whatever the full story about causes may be, religion inevitably promotes particularly bad features of war and terrorism, such as their ferocity and duration. This talk will offer a critical appraisal of these presuppositions and their influence.