The Movie IS Subtle (Spoilers, of Course)
At least one poster has opined that the problem with this movie is that it lacks subtlety. I think this fails to give it due credit.
I just watched it last night for the second time. The first time around I also fell into the trap of taking the images at face value, but on the second viewing, I came away with a different opinion. There are several things that do not add up as the story evolves.
First, as pointed out by a number of posters, it blurs the distinction between demons (supernatural) and sinners (human). This is a mistake that a young boy might make and carry through into adulthood to justify his homicidal tendencies, but it is not likely a mistake god would make in revelations to his agents. Hence it is not a given that the victims actually are demons – only that Adam believed they were. This is a strong clue that the story is being told from Adam’s viewpoint, including the visuals.
Second, Adam’s story regarding Fenton’s Hand of God guilt is not credible. He states that Fenton was leaving “Hand of God” notes to draw Adam to him. Why would he do this? Fenton knew where Adam was. Everybody knew. He was the sheriff. Maybe Fenton did not kill those people, and was set up by Adam to close the case.
Third, did you notice the graves in the rose garden? According to Adam’s story, they have been burying beheaded corpses there for years in shallow graves. The rose garden was public land and was landscaped. This means landscapers, gardeners, and picnickers attending it constantly. Are you trying to tell me that no one even noticed all of these grave-sized mounds cropping up like dandelions, particularly in view of all the people in nearby towns going missing? Moreover, the grave mounds shown to the FBI agent were recent. Over time, dirt mounds tend to settle back to ground level, but the ones the FBI found were all knee high. Recent. So when were they really dug?
Fourth, the picture given by Adam of their life prior to their father’s conversion was story-book perfect. Dad was perfect, life was perfect, the brothers were perfect, etc. Yeah, right. The story they gave to explain their Dad’s disappearance was that he simply didn’t come home after work. Actually, this might have been the truth. Maybe, on his own, he could not deal with the incipient insanity of his sons, and it’s only in Adam’s retelling that rationalizations were given for his rejection of them. Again, as many posters have pointed out, Adam is an unreliable narrator.
Fifth was the mother-murder. Are we actually supposed to believe that the FBI agent stabbed his mother umpteen times, splattering blood all over the block, and then, because the murderer was never caught, he became a cop? The murder was way over the top and looked like a deranged mind fantasizing Hitchcock’s “Psycho,” which, no doubt, Adam had seen. The murder may have happened, but not by the FBI agent. It was a fabrication by Adam, just like the delusions he experienced with the rest of his victims to justify their executions. Actually, the agent’s appearance on the hit list was gotten from the newspaper stories which identified him as the lead on the Hand of God case.
Sixth, and this is a big one, if you watch the last scene carefully, you will notice that the score is not "Happily Ever After" music. It is very ominous with tension undertones. This story is not over – particularly with the girlfriend pregnant.
A more reasonable view of the movie is that Adam made up most, if not all of the narrative, including some of the visuals which many viewers took as reality. Even the so-called flashes of the sins are nothing more than the psychotic visions of a madman, and the only reason we see them is that the story is told from his perspective. Think back on The Usual Suspects at the disconnect between some of the visuals and the narration. Even the blurring of the videotapes is explained by the electrical storm that night causing the taping equipment to malfunction.
There is nothing supernatural, or religious (same thing), in the movie – just madness subtly portrayed. The subtlety, of course, lies in requiring the viewer to filter the story elements to distinguish between reality and Adam's delusions.