The past two decades have witnessed pervasive anxieties in US Muslim communities around a perceived crisis of faith. As Zaid Adhami argues in this richly textured ethnography, these concerns are fundamentally about the pressures and dilemmas of authenticity—what it really means to be a Muslim. While discussions about authenticity in Islam typically focus on maintaining tradition and competing claims to "true Islam," Adhami focuses instead on the powerful idea of being true to one's own self and what it means to have genuine belief. Drawing on extensive conversations with American Muslims and careful readings of broader communal discourse, Adhami shows that this drive for personal authenticity plays out in complicated ways. It can produce deep doubt while also serving as the grounds to affirm tradition. It can converge with revivalist modes of piety, but it can also prompt emphatic challenges to communal orthodoxies. Through vivid storytelling and sensitive analysis, Adhami illuminates why religious doubt is often a source of intense anxiety in today's world and how people maintain their faith despite such unsettling uncertainty.