Someone has calculated that, on average, a new book on terrorism is published every six hours. Since the 9/11 attacks, a sizeable minority of these books focuses on terrorism “and Islam”, or some other religion or religions. Who, then, can fault James Lewis if he struggles to find an original framework or thesis for his collection? Rather, we are left to explore issues bedevilling the very use of the two nouns connected in the volume’s title. Is religion – such a contested term to begin with – really the motivator of violence committed in service to a purportedly sacred cause?