Whatever the problems posed by greedy companies and other economic actors for the effective conduct of diplomacy, it is easy to assume that they cannot be as bad as those posed by crazy religions, denominations and their members. The idea of “crazy religion” flags an apparently new and pressing challenge to the conduct of contemporary international relations. Since the attacks of “9/11” and subsequent events, largely in the United States, Western Europe, South West Asia and the Middle East, insurgent sects have appeared among peoples like hot cinders falling upon forests which, for reasons that to educated received opinion remain shocking and unfathomable, are dry and ready to burn. In a world rendered increasingly intelligible, controllable and exploitable by the application of scientific enquiry and technological discovery to human affairs, growing numbers of people are attracted to pre-scientific accounts of the world and their place within it. Not only that, they are prepared to be mobilized and to act on the basis of these understandings. What does this development tell us about people, the impact of modernization upon them and the prospects for peoples living peacefully together? The international relations of the Middle East often illustrate the problems posed by religion for diplomacy in their sharpest form. How does one negotiate with people who believe their title to a contested piece of land comes from God, and how do they negotiate with people directed by false gods or no gods at all?