There was an occasion in the 60s where a bunch of hippies surrounded the Pentagon and tried to exorcise the demons. It didn't work. Despite their valiant effort, not much happened that day.
Nevertheless, I am one of those Christians who believes in angels and demons. But I think the traditional Christian understanding of these things needs a major makeover. Seems to me the Tempter comes in many forms, and is just as likely to don a three-piece-suit and wingtips as he is to have horns and a pitchfork. And perhaps the angels look more like the bums in the alley than the feathered white babies on Hallmark cards.
One of my favorite demon stories from the Bible is about a guy named "Legion." As the story goes, Jesus is walking through an area near the sea of Galilee and meets a dude who is in chains, violently possessed by demons. When asked his name the fellow says, "My name is Legion, for we are many." Jesus drives the demons from the man into a bunch of nearby pigs that charge into the water ...1