As any observer of the Islamic world—or regular listener to Akbar’s Chamber—will know, there are a dizzying variety of different forms of Islam. Yet every Muslim who follows one of these different versions believes it represents the true version of the faith. This begs the question of who gets to decide what is, and isn’t, Islam? In other words, who has the religious authority to define Islam? In this episode, we explore the social, historical, and doctrinal dimensions of religious authority through the lenses of anthropology.  Step by step, we unpack the key components of religious authority, from revered historic founder figures to their living representatives, along with the crucial components of respected texts and institutions that range from mosques and mystical orders to political parties and states. While looking at Islam from the analytical outside of the social sciences, we also examine how this approach relates to two foundational Islamic concepts: the Sunna (or Model of the Prophet Muhammad) and the Jama‘a (or Muslim Community). Nile Green talks to Ismail Fajrie Alatas, author of What is Religious Authority? Cultivating Islamic Communities in Indonesia (Princeton University Press, 2021).