You don't have to wait for the (probably soon?) DVD release of Deliver Us From Evil to see what appears to be one of its special features. Slated for theatrical release July 2, the movie has Eric Bana playing the real-life Ralph Sarchie, an NYPD cop who was also a demonologist.
Watch the 15-minute featurette Sarchie below, which has some choice quotes from the real-life cop / demonologist, including:
"You singled yourself out, now who do you think Lucifer is going to be looking at? When you stood up and gave him the finger? Well, that's basically what you do when you expose the devil. You're standing up and you're going, YO!"