@Dead CruiserHe's ac th ually more of a Naythiest, if there is a "God" they are a shoddy craftsman at best and will just be generally unimpressed with all their self righteousness.
I think I'm going to revise Trev one last time and lean a little harder on the Slasher/Humanist angle. Tone down the fiery demon stuff and pick up demonic representations of the first weapons used in murder. Obsidian knife, bronze sword, bonetiped spears/javalin, 6th century Chinese hand cannon as the predecessor of guns, stuff like that. Their only supernatural properties other than looking hella cool/scary is their tougher than they should be, able to eventually regenerate, and cut through stuff they logically shouldnt due to the bloody symbolism of their long history of use to end other human lives. These are what allowed him to Doom Slayer his way through Hellscape.
EDIT: Finished and I'm honestly pretty satisfied with where they are at.