Originally Posted by
Serpentine
The first (and only) campaign I've ever actually finished as a player had a fallen angel BBEG. I can't remember whether the angel himself was still considered Good (may have never known, but I expect he at least fell to Neutral), but his minions included a large number of Lawful Good Paladins who believed they were doing the bidding of a true celestial being.
...but that could be your reason for "leading a revolt against heaven"? Somehow it's been infiltrated by a truly Evil creature that is directing the still truly Good celestials to Evil ends. Maybe you find real evidence for the reality of the Burning Hate...