Demons are the Pagan Gods of Ancient Times

[Byrd]

Bad vs good is pretty much universal, it seems to me. What represented good? What was the anti-demon?

Actually not as universal as you might think.  In ancient Egypt they had a "universal law' (the law of Ma'at) which in its most basic form is "don't be a jerk to ANYone or anything."  It's more nuanced than that, but that's the quick and dirty form.  The gods were all good except for Set, who was problematical and even he had a redemption arc (until the Christians got ahold of him.)

Evil things were caused by demons but humans made their own choices.  There was no such thing as a demon spirit that tempted them into doing bad stuff.

Nor do Native American beliefs (of any that I've studied) see that distinction... people do bad things but there's no God of Doing Bad Stuff.   Same with Norse beliefs.

Most societies saw the evils as something that just happened.  Maybe you weren't adequately pious when you were cleaning yourself for temple.  Maybe you forgot a protection amulet.  Maybe you were just unlucky.

And evil was always a gray area.  Killing is bad but if you're killing someone to protect yourself, your community, your family then it's acceptable.  They understood it as a range and not a dichotomy.

In many societies, the deities were all good and beneficial.  In some (Greece and Rome, I'm looking at you) the gods seem to be a bunch of Frat Boys with no moderator to rein them in.