We may think we know what defines religious fanaticism: violent action undertaken with dogmatic certainty. But the term , from the European Reformation to today, has never been a stable one. Then and now it has been reductively defined to justify state violence and to delegitimize alternative sources of authority. rejects the simplified binary of fanatical religion and rational politics, turning to Renaissance literature to demonstrate that fanaticism was integral to how both modern politics and poetics developed, from the German Peasants' Revolt to the English Civil War.