Heresy is at truth taken too far, or a virtue emphasised to the detriment of others - paraphrasing Chesterton whom Tolkien almost certainly read given their similar locations/religions. It's a theme you see with Sauron's love of order in particular.
I think a lot of the Maga people pretty much take this view of DEI or Nazi hate. That diversity was originally good when it was about helping minorities but not when hurting whites, however tricky those are to separate in zero sum environments.