Belief has built civilizations, sustained communities, inspired sacrifice and given people reasons to endure the impossible. It has also given human beings permission to cross lines they once believed should never be crossed. In this volume, Dr. Mozelle Martin follows that transformation across more than 2,000 years of religious and political history. From Carthage and the Sicarii to medieval heretics, Münster’s New Jerusalem, Sabbatai Zevi, the Dönmeh, Freemasonry, the Hellfire Clubs, the first Saudi state, the Skoptsy and the Bavarian Illuminati, the evidence reveals something more complicated than a history of “cults” or strange beliefs. Some accusations collapse when hostile testimony is compared with archaeology and surviving records. Others become more disturbing under scrutiny. This book separates belief from conduct, secrecy from conspiracy, ritual from violence and religious difference from extremism. It examines what people actually did, what their enemies claimed they did and the point at which faith, prophecy, purity, political mission or sacred authority began overriding ordinary moral restraint. The most dangerous belief is not necessarily the strangest one. It is the belief that grants permission to stop questioning.