This book focuses exclusively on conspiracy theories that are based on deceitful narratives of the past. This book illustrates not only why and how conspiracy theories have been able to deceive people, but also what we can learn from them about a particular historical context or the long-term trajectory of the fears and hatreds they mobilise and amplify. This book also focuses on reconstructing how a specific conspiracy theory has taken shape within a religious tradition and how it has acted against a religious group. By using a distinctly historiographical approach to reconstruct how historically relevant conspiracy theories have developed within religious traditions, it deconstructs the lies, whether intentional or spread in good faith. But most importantly, this volume shows the historicity of specific deceptions and the process of invention and fabrication at the heart of the narrative machinery of conspiracy theories. It is an important read for scholars interested in conspiracy theories and religion, especially in a European context.