Frailty could have been such a fantastic horror film, but the third act is such a mess. Before that third act, the film had remained subtle for the most part, as well as elegant, often relying only on atmosphere and the actors' performances. It's great. Then they introduce a contrived and unnecessary plot twist, one that begins undoing everything that was great about the first two acts. One need not look any further than those visions/flashbacks of the "demons" committing various "sins" to see how it absolutely wrecks the atmosphere and tone that the film had in place. These scenes are pure schlock and are a detriment to the film and its story. Also, the reveal of Agent Doyle's past is stupid and seems to be nothing more than an attempt to rip off Fincher's Se7en. It feels incredibly lazy and tacked on to have this FBI agent be on the kill list of this religious serial murderer.

Additionally, the twist hurts the character that is 'Dad Meiks', a character that was both frightening and sympathetic, something that is seldom seen in horror films. The twist, though, creates a supernatural justification behind Dad's actions, which ultimately hurts previous scenes that were initially either disturbing or sad. The scene of Dad killing the child murderer (the individual that he takes down in the parking lot) is no longer as impactful when it's all but verified that the dude is an actual child rapist/killer. I mean, it's a child murderer, the fuck do I care if Dad is killing this guy on the authority that is God? When you confirm to the audience that God is real and that the protagonists are doing his work, then all ambiguity is left at the door and it's no longer thought-provoking or scary. When first seeing the scenes where Dad abducts and then kills this man, it's far more disturbing, and it's disturbing due to the fact that you don't know whether or not this man is guilty of any crime. The initial implications behind all of Dad Meiks' violent acts was that he was losing his sanity and then justifying these murders only in his mind, and in doing so was exposing his two sons to this world of perversion and chaos. That shit is scary. Him murdering demons for God is not.

But I don't know, that's just my two cents. It's completely cool if you're good with the twist. For me, though, it really fucked up the film. It's a shame, because again, I really do love the first two acts.