This article uses a critical discourse and documentary analysis to explore “Good and Evil” narratives in Islamic State (IS) media and in the official policy statements of the United States, Australia and the United Kingdom. The analysis initially considers how IS and Western governments define the other as “Evil” drawing from premodern Manichean and Abrahamic religious conventions. It then interprets how these entities subscribe to a post-Enlightenment ethic that associates the triumph of “Good” over “Evil” with science, reason and technological innovation. Distinct from similar analyses that emphasise the persuasive power of religion, this article reflects on how IS and Western governments use conflicting religious and philosophical imperatives to articulate their strategic political agendas. It further interprets how these agendas become ideologically convincing, through reflexive communication.