Possession by a malevolent spirit sounds like a horrific nightmare or bizarre fiction, but history has certainly shown that it isn't such a far-fetched concept. The fear of these possessions stems from Christianity and other religions. They had treacherous repercussions, such as witch hunts in Europe and the United States, and attempted exorcisms. Murderers even used the guise of demonic possession as an excuse for their crimes. Readers poring through...