Yet every coercive religious group harbors one telltale trait: untoward secrecy. As opposed to a cult, a religious culture ought to be as simple to enter or exit, for members or observers, as any free nation. Members should experience no impediment to relationships, ideas or travel, and the group's finances should be reasonably transparent. Its doctrine need not be conventional—but it should be knowable to outsiders. Absent those qualities, an unorthodox religion can descend into something darker
Mr. Horowitz, the editor in chief of Tarcher/Penguin in New York and the author of "Occult America" (Bantam), is writing a history of the positive-thinking movement.