4) Taiping rebellion - autonomy-requesting rebels
Uh, uh, I think you're forgetting that Hsiuchuan thought he was Jesus's brother and thought that the Manchus were devils - this whole thing was thought up when Hsiuchuan was sick and sad and read a Holy Writ that a Protestant priest gave him. The Heavenly Kingdom was a Christian country - Confucianism, Buddhism, and Folkfaith were banned. And this is 3rd bloodiest. However:
10 bloodiest deathbringers:
1: Mongol Wars
2: Second World War
3: Taiping War (faith-started)
4: Three Kingdoms' War
5: Black Illness
6: European-American wars
7: Ming's End
8: An Lushan's Revolt
9: First World War
10: Dzungar Revolt