This has been an interesting discussion so far. As someone who hasn't touched a d20 since the 1980s, just how baked into D&D are the alignments? Spells like Detect Evil are still adjudicated by a human referee, so variations like detecting-only-really-evil-undead shouldn't be much of a problem. Or having them show up as "evil" due to the unnaturalness. Whatever makes sense in that world. My recollection was that created undead were considered Neutral due to being mindless, but the DM would typically let a character detect the alignment of the spell animating them.
The last tabletop game I'd played was second edition Rolemaster, which isn't so much a game as a game construction kit for OCD gamemasters. A handful of spell lists were labeled Evil, but it was up to the GM to determine what that meant. They were somewhat more powerful, so I decided they were "spells maximizing power at the expense of safety" and thus soul-corrupting, but could be used by a "good" character under the right circumstances (which is to say with sufficient roleplaying by that player). Except that they were expressly illegal in one of the countries, pretty much because they had rules about everything.
That world had a relatively simple cosmology with three main religions.
The first religion worshiped the God of Law, whose enemies were the God of Chaos and the God of Evil.
The second religion worshiped the Lord of Freedom, whose enemies were the Lord of Stasis and the Lord of Corruption.
The third religion worshiped the Master of Power, whose enemies were the Master of Conformity and the Master of Confusion.
As you might have guessed, they're all talking about the same three deities. There was also a cult of "witches" who believed all three of them were facets of the same being. That these "witches" were heretics was about the only thing all three major faiths agreed upon.
Would such a thing even fit into D&D?