User blog comment:BeholderofStuff/Pure Evil Removal Proposal: The Devil (theology)/@comment-2059440-20190830004936

from a strict monotheistic view he can never be purely evil because a fully omnipotent deity allows him to do what he does.. I know there's the whole "free will" thing but in some texts free will is stated to be mostly for humans and Hell is designed for rogue angels rather than people..

plus many of the older texts have Satan as a kind of semi-divine (if dark) figure who has either asked God to allow him to do evil to test man or works as an "adversary" as part of God's over all plan.

the Devil as we know him today (big red satyr who is the near-equal of God and does evil to oppose God and rules over a fiery realm where he can torture sinners forever) is mostly a medieval addition.