The conviction that demons exist—and that they exist to harass, derange, and smite human beings—stretches back as far as religion itself. In ancient Mesopotamia, Babylonian priests performed exorcisms by casting wax figurines of demons into a fire. The Hindu Vedas, thought to have been written between 1500 and 500 b.c., refer to supernatural beings—known as asuras, but largely understood today as demons—that challenge the gods and sabotage human affairs. For the ancient Greeks, too, demonlike creatures lurked on the shadowy fringes of the human world.
But far from being confined to a past of Demiurges and evil eyes, belief in demonic possession is widespread in the United States today. Polls conducted in recent decades by Gallup and the data firm YouGov suggest that roughly half of Americans believe demonic possession is real. The percentage who believe in the devil is even higher, and in fact has been growing: Gallup polls show that the number rose from 55 percent in 1990 to 70 percent in 2007.