Ibn Taymiyya (1263–1328) of Damascus was one of the most prominent and controversial religious scholars of medieval Islam. He called for jihad against the Mongol invaders of Syria, appealed to the foundational sources of Islam for reform, and battled against religious innovation. Today, he inspires such diverse movements as Global Salafism, Islamic revivalism and modernism, and violent jihadism. This volume synthesizes the latest research, discusses many little-known aspects of Ibn Taymiyya's thought, and highlights the religious utilitarianism that pervades his activism, ethics, and theology.