Paramount’s The Devil Inside is just about to hit theaters and while I haven’t seen it yet – I’ve talked to a very experienced person who has.

Reverend Bob Larson has been pretty busy the past 30 years. He claims to have performed over 15,000 exorcisms during that time. More than one a day on average. I had the chance to speak with him earlier this week about his “real-life” experiences and how the movies stack up against them. Particularly The Devil Inside.

While I’m not entirely sure I believe in demonic possession myself, Larson certainly claims to and was willing to speak at length about it.

“In 1989, emergency responders received a 9-1-1 call from Maria Rossi (Suzan Crowley) confessing that she had brutally killed three people. 20 years later, her daughter Isabella (Fernanda Andrade) seeks to understand the truth about what happened that night. She travels to the Centrino Hospital for the Criminally Insane in Italy where her mother has been locked away to determine if her mother is mentally ill or demonically possessed. When she recruits two young exorcists (Simon Quarterman and Evan Helmuth) to cure her mom using unconventional methods combining both science and religion, they come face-to-face with pure evil in the form of four powerful demons possessing Maria. Many have been possessed by one; only one has been possessed by many.”

The Devil Inside hits theaters on January 6th, 2012. Hit the jump to check out the interview and a video of Larson performing an “exorcism”!What are some of the differences between the exorcisms we’ve seen on film and the real thing? “Watching the cinematic portrayal through the years has been interesting. The original Blatty movie (‘The Exorcist’) didn’t get much right. ‘The Exorcism Of Emily Rose’ got a little closer, ‘The Rite’ got a little closer. At least the first half of ‘The Devil Inside’ probably is the closest to an actual portrayal of what goes on during the investigative process and psychological considerations of what demons actually do. This is probably the closest anyone has been to it. I like the fact that in this movie you’ve got a coupe of very serious priests who are into seriously documenting what they do. They take a very scientific approach to it, even calculating the dialation of the pupils which is one of the way we detect possession. So whoever was writing the script (Brent Bell, Matthew Peterman) got that right!”

What are some of the physical and psychological symptoms of someone who has been possessed? “We get quite specific in studying body language. To watch the face, to watch the eyes. To watch for initial indicators that an evil spirit is being aroused as you begin the exorcism process. It’s the job of a demon at that point to hide. Because when a confrontation is taking place they don’t want to be expelled, so they’re going to try and find a way to circumvent that. As the process continues we can use holy objects like holy oil, holy water, crosses or a bible to antagonize the demon. You watch to see a response. What you’re after is a manifestation, to get the demon out in the open so you can communicate.”

Are some people more at risk for possession than others? Certain personality types? “It’s primarily a factor of ones past. One of the unanswered questions of this movie is “why this woman?” We don’t really know that. Obviously the possession was very very real and what we discovered was that highly traumatized people, people who have often been victims of violence or sexual and physical abuse tend to be a lot more susceptible to demons. They’re just a lot more emotionally fragile.”

And how many exorcisms have you performed? “I’ve done a documented 15,000 plus.”

Wow. “That’s a lot but you gotta remember that’s spread out over 30+ years. I do this virtually seven days a week and many many times in most cases”

What are some of the most memorable or intense ones? “That’s a challenge because there are so many hundreds of them. The more violent ones stand out. The most serious physical damage I’ve had is having my ribs broken. That happened to me one time in South Africa. But a lot of it is psychological warfare. In this movie for instance, the moment you see in the trailer with the dislocation of the limbs and that sort of thing.”

Have you seen something like that happen before? “I have. It’s not a common thing, but I’ve seen bodies twisted in ways that are incomprehensible. Of course I’ve seen levitations in the middle of exorcisms, not quite what you see in ‘The Exorcist’ though. One of the things I like about ‘The Devil Inside’ is that the arousing of the demons is very very authentic to the experiences I’ve seen.”

If you had to clear up one misconception about exorcism, what would that be? “I would say that the biggest misconception is that it’s terrifying to the person who performs the exorcism. If it’s terrifying, you better not do it. It’s trouble. You’ll be in over your head. In ‘The Exorcist’ the priests go after the thing and they’re scared to death to do it.”

And it doesn’t end too well for them. “It does not end well for them at all. I understand why, from a cinematic standpoint, that makes the move interesting. But it’s not at all fearful. In fact I’ve trained my 17 year old daughter and four of her friends to do it“.

Where do the demons come from? Is it an extension of the person’s internal struggle? “No. Exorcism is the belief that Satan has his representatives, disembodied invisible actual spirit beings, who are looking to take residence in a human body. They are looking for people who are vulnerable that they can use. It’s clear to me that much of the crime and violence that we see today are demon possessed but not diagnosed. Of course mental illness enters into it as well. But a lot of people are abused, and the hate builds up in them and gives the demon what we call “the legal right” to enter them.”

Have you encountered the same demon more than once? “Many times. Though, you have to understand, demons have rankings. If you encounter a demon of murder, it’s not necessarily the same demon, just a demon who was assigned the task of murder. However I have had demons who have looked at me and said, “we know each other.” And they have actually named times and places that the person I’m working with possibly couldn’t know. Other exorcisms I’d conducted in other people years ago.”