What is the fine-grained topic of the following text: One of the founders was William Saunders Crowdy, an ex-slave and Civil War soldier who had "a vision" that not only turned his hair white (not sure if the vision took place at a hairdresser's), but showed him the true path in life: to lead his people to the one, true religion. Only return the topic.
William Saunders Crowdy's vision and foundation of a religion