The Last Exorcism
(2010)

Cotton Marcus (Patrick Fabian) is a well loved minister from the small town.  Cotton's family has always had a history with performing exorcisms, however Cotton admitted that he did not truly believe in demons.  He performed exorcisms (usually using parlor tricks) to provide comfort for the supposedly possessed, but he decided to stop after he read how an autistic boy was killed during an exorcism.  Cotton allows a documentary crew to follow him as he performs one final exorcism on a girl named Nell Sweetzer (Ashley Bell) in the hopes that he can show how demonic possession is merely a psychological problem.

Cotton performs two "exorcisms" on Nell and eventually becomes convinced that Nell's violent behaviour is the result of the psychological trauma caused by her being impregnated by a boy that worked at a local cafe.  Cotton then leaves Nell in the care of the local pastor and her father.  However, Cotton realizes something was off after he visits the cafe and finds out that the boy who supposedly impregnated Nell didn't know her (and was gay).

Cotton returns to Nell's house and finds pentagrams and "666" written all over the wall.  Cotton goes out into the woods to find that there is a Satanic ritual going on lead by the pastor, and Nell is tied to an alter (with her father tied to a tree).  A demonic-looking fetus is pulled out of Nell and thrown in the fire, which grows into a large demonic shape.  Cotton finally believes and goes to confront the demon, but it is too late and Cotton and the camera crew are attacked and killed, with the final shot consisting of the cameraman being killed by Nell's brother.

Thanks Sean!