The nineteenth century was a time of extraordinary scientific innovation, but with the rise of psychiatry, faiths and popular beliefs were often seen as signs of a diseased mind. By exploring the beliefs of asylum patients, we see the nineteenth century in a new light, with science, faith, and the supernatural deeply entangled in a fast-changing world. The birth of psychiatry in the early nineteenth-century fundamentally changed how madness was categorised and understood. A century on, their conceptions of mental illness continue to influence our views today. Beliefs and behaviour were divided up into the pathological and the healthy. The influence of religion and the supernatural became significant measures of insanity in individuals, countries, and cultures. Psychiatrists not only thought they could transform society in the industrial age but also explain the many strange beliefs expressed in the distant past. Troubled by Faith explores these ideas about the supernatural across society through the prism of medical history. It is a story of how people continued to make sense of the world in supernatural terms, and how belief came to be a medical issue. This cannot be done without exploring the lives of those who found themselves in asylums because of their belief in ghosts, witches, angels, devils, and fairies, or because they though themselves in divine communication, or were haunted by modern technology. The beliefs expressed by asylum patients were not just an expression of their individual mental health, but also provide a unique reflection of society at the time – a world still steeped in the ideas and imagery of folklore and faith in a fast-changing world.