Brilliant But Flawed

I love this film but there are some problems with it

The main one was the definition of a demon. Fenton is a demon but hasn't done anything bad so it can't simply be sinning. So did these people who were demons know they were demons or were they controlled by demons or did they house a demon spirit that would eventually take control at some point?

The father says that demons are already here and the war has begun but this would suggest that they are acting to prepare the way for the devil but from what we see, they're simply people doing bad things. How is that a war. Haven't people always done bad things? There appears to be some confusion about wether or not demons know they are demons

The cop for example. If he was a demon then why wouldn't he be more suspicious of Adam and anticipate a potential threat. Instead, he simply behaves like a normal human jack ass who does not know he's a demon and doesn't see where things are heading. Surely a demon would suspect something. He even still looks perplexed when Adam talks about his mother. Even when they both witness the vision of the cop killing his mother, the cop still seems surprised at it. Why would a demon do that?

I think that is a plot convenience and not fully explored

Part of me still wants to believe that the film is a clever and subtle criticism of blind belief. That in truth, the father and Adam were both simply psychopaths and the story we hear from Adam is nothing more than his bizarre mental illness version of events. Sadly however the film makes it clear that this is not the case and that they really were doing the work of a God

I don't mind the twist but I think to be a truly great film, a better twist would have been for clues to have been left that hint at the father and Adam being insane (but they're not there)