Another 'found-footage' fake documentary. This genre conveniently now includes any type of movie that features the use of a hand held camera in the film as a prop for the benefit of driving the story (think Chronicle, for example). Here, a documentary is being filmed about Isabella Rossi played by Fernanda Andrade, the daughter of Maria Rossi, a woman alleged to have killed three people during an exorcism which was being conducted on her. Found innocent due to insanity, Maria is sent to a mental institution in Rome and this is where Isabella's documentary really begins.
The inherent problem here lies with the viewer. You can take from this what you will and this will differ depending on your religious bent. There is no equivocal judgement to be passed on the authenticity of this story. There is never any claim that this is even a true story, but the suggestion of the actions taken during exorcism are implied and the reaction to the subjects of these exorcisms are also implied. This begs the question of where the information is gathered from and if this is indeed a reliable source, then the actions of the subject could naturally also be described as authentic.
If this is the case then it is almost certain that these subjects of exorcism are nothing more than troubled, psychologically damaged people who, for one reason or another, display the traits the church deems symptomatic of demonic possession. Why am I so sure of this? Well, I could come up with more disgusting things to say to a priest given only five minutes to come up with the material. A true demon, should one exist, I imagine, would be able to come up with something far more revolting than a hastilly scribed scene from a Stephen King novel. And here lies the viewer's problem. Some audiences will be shocked by what they see and hear, yet others will have it wash over them, unmoved, having seen all of this before and much, much worse besides.
Not only that, but how do you successfully portray, in terms of confident and convincing recreation, the actions of someone possessed by something that may, in the eyes of the viewer, not even exist? It makes the actors task more than merely difficult. It's like asking Keanu Reeves to play an alien here to save the planet from deadly and careless humans. What a notion!
All you can really say about The Devil Inside is that it brings no new notions or ideas to the subject of exorcism whatsoever and those ideas that is does display are thin at best. The acting is impossible to quantify given that it's like asking your opinion on marmalade when all you've ever eaten is jam. The acting seems authentic for what we have been taught to believe is the sign of possession, but doesn't that just make an example of our collective ignorance?
For a budget of a million dollars, the money seems to have been spent wisely enough and there is a suitable amount of thrill for the investment. The audience will leave unconvinced and unmoved by the film, however, and I would struggle to recommend it to anyone, even the god-botherers amongst you. This will do little to aid your doubtlessly righteous cause, more make a mockery of something you are supposed to fear.
Crap, overall... There, I've said it, actual crap.