In Divine Divinity, there were the Seven Good Gods, but there was an Eighth god, the Lord of Chaos. He created a race of sentient beings to be his slaves. Those beings were demons. That made the Good Gods unhappy and they tried to banish him. That didn't work so they created their own races to help battle the demons, and eventually they tried to banish the Lord of Chaos from reality to another plane. But he got stuck partway through there, and a place formed around him. That's what Hell is and that's where most of the demons got banished to.

That's how it was, at least.

But whoops this game completely retcons this by saying that before all that there were the Eternals, which something something something something - I didn't have Fane and I didn't even bother trying to understand any of that Eternals stuff. Apparently there were seven Lords of the Eternals (forgetting about the Eighth) who stole source to open a hole in the void and then they threw all the other eternals into that hole somehow?

I dunno, whatever...