Cotton's Redemption (spoilers)
It was pretty clear that the main themes of this movie were Cotton's reaffirmation of faith which I felt to be emotionally powerful given his actions at the end of the movie.
Cotton was introduced as a show man and performer who tossed words around with little meaning or heart behind them. A sceptic of demons and exorcism. He performed exorcisms somewhat like his sermons, to ease the mind of 'delusional people'. Not to say he didn't believe in God, he just gave him lip service.
When Cotton first meets Caleb on the road, Caleb tells Cotton to turn around and makes it clear Cotton is not welcome. He does this because he himself is a demon worshipper and probably felt threatened by a pastor coming to his house. This leads to one of the few scenes I actually found funny. After performing the first exorcism, which was a total production, Caleb realizes it and goes up to Cotton laughing and says something to the effect, "We won't have any problems now." Because Cotton does not believe the words they are simply being said as a performance. During the second exorcism in the barn Cotton is reading from Ephesians and Abalam yells out "Words, words, words!" for the same reason.
After a bunch of people lie to Cotton, despite him telling everybody several times not to believe demons and lies, he thinks everything is explained and heads home. Finds out the truth from gay waiter, heads back to discover a satanic ritual going on with Nell and her father tied up.
Now comes the scene that I really like. There is all this evil around and it is dark and scary *beep* is happening. The camera man turns to Cotton. Cotton seems to be in deep thought grasping the crucifix (which was previously a prop in his "exorcism") he stands up and strides out into the field to help the innocent Nell with only faith and God as his ally.
Everything after that picture of Cotton's silhouette in the night against the fire with his crucifix held high is not important.That is when the movie really ends, with his redemption.
Just watched "The Possession" the other day and thought this movie was a lot better because of the above story arc.