Ghosts. Railroads. Sing Sing. Sex machines. These are just a few of the phenomena that appear in John Lardas Modern’s pioneering account of religion and society in nineteenth-century America. This book uncovers surprising connections between secular ideology and the rise of technologies that opened up new ways of being religious. Exploring the eruptions of religion in New York’s penny presses, the budding fields of anthropology and phrenology, and Moby-Dick, Modern challenges the strict separation between the religious and the secular that remains integral to discussions about religion today. Modern frames his study around the dread, wonder, paranoia, and manic confidence of being haunted, arguing that experiences and explanations of enchantment fueled secularism’s emergence. The awareness of spectral energies coincided with attempts to tame the unruly fruits of secularism—in the cultivation of a spiritual self among Unitarians, for instance, or in John Murray Spear’s erotic longings for a perpetual motion machine. Combining rigorous theoretical inquiry with beguiling historical arcana, Modern unsettles long-held views of religion and the methods of narrating its past.