Where's God or benevolent forces in PA universe?

This movie was terrible and not canon in my eyes, but I'll try to answer your question, while I see Christianity as a fairy tale (not the concept of a god or afterlife) by it's logic Demons are free to do whatever they want until Judgement Day, but there were religious items used against Toby in the previous films like when Katie was clutching the cross with her hands until they bled and the director even mentioned that the cross was the only thing keeping her safe but then Micah burns it, Kristi is exorcised with a cross, and in the beginning before the mexican maid is kicked out she uses chants while using 'sage' everywhere in the house but the dad uses a pillow to get it all out the door, not just even 'religious' but spiritual items that ward negative energy away, even non-spiritual like just bad feelings which are technically caused by or worsened by Toby's presence.

Actually this is a very common trend in horror movies about dark forces empowering humans like Blair Witch, The Omen, Drag Me To Hell, that's all I could think of but yeah, it's not a new concept and honestly more fun to play around with the idea of evil winning against good like every other typical movie that has good defeat evil, just my thoughts.

And the extermination not working was just a plot hole, the movie broke it's own logic by a solution to banish Toby yet just ends up getting them killed, but if you think about it in the previous films Toby became too powerful and his plans to use the first born males as a demonic army in The Marked Ones would likely succeed, who knows though, we may never know what truly would of happened in the original script written by the original writer Chris Landon with assistance from Ariel Schulmen and Henry Joost.

In the Old Testament, the Hebrew god Yahweh was the author of all "evil", pain, suffering, lies, etc. As the omnipotent god father figure of all, EVERYTHING could be traced back to him. This is why many stories say that an evil spirit went out from the LORD to such and such character and caused him an affliction, or went out to a man and told him a lie. And in the story of Job, ha-Satan (the-Adversary) goes about accusing a devout man of being less than perfect, and goes to Heaven to ask the god figure if he can afflict the man with all sorts of suffering in order to push the man to the limit and make him rebuke the god, and Yahweh says sure, no problem. Yahweh sits idly by as ha-Satan, much like Pinhead from the Hellraiser movies, essentially rips Job's soul apart. Far from being Lucifer and having allegedly been cast down from Heaven, ha-Satan is described as being just as much of a fixture of human events as humans themselves, as well as still very much an active member of the god's heavenly court. And the OT god loved it so. He blessed the man Job in the end, but he did nothing to stop all of his tremendous suffering--in fact, he authorized all of it.

The New Testament revises things by pointedly blaming suffering and evil on the devil figure Satanas or to-Diabolos, and somewhat distancing such suffering from the god character Theos. (He's supposed to be the good guy, after all, so it wouldn't do to overtly depict him as the source of every evil thing, too, anymore, would it?) Nevertheless, there are still stories of demons and devils possessing and terrorizing people, which Theos, Iesous (Jesus), and the Apostles only occasionally intervene against. Other people are not so lucky and just get screwed. And apparently, the NT god loves it so, as well.

The Bible god doesn't appear to really care about people's suffering all that much, unless there is a dramatic propaganda moment to make out of it. Then he might step in. He's like a politician looking for a photo op.

I suppose Father Todd should've prayed a little more and told Theos that this particular demonic possession event was being videotaped, which could've been digitized and uploaded, which would have allowed it to go viral worldwide. Maybe then Theos would've cared enough to exterminate this particular demon.

Theos probably needs a better campaign manager and publicist. He totally blew this opportunity for some great pub. Bad optics, dude.