Professor Peter Henne published a new book recently. Religious Appeals in Power Politics (Cornell University Press, 2023) looks into an under-studied area of international relations: what happens when states try to use religion as a tool in interstate crises. In contrast to those who are skeptical of or champion religion’s importance, Henne argues that appeals to religion in interstate crises are a potent tool that can easily slip out of a state’s control. He demonstrates this with case studies of the 1960s Saudi-Egyptian rivalry, US religious outreach during the Global War on Terrorism, and Russia’s efforts to gain support among conservative actors in the West. The book can help move both mainstream security studies and the study of religion and international relations forward through its novel theory and approach.