Warhammer 40K: Every Faction Ranked From Least To Most Evil
4. The Sisters Of Battle
If the Emperor had his way the Imperium would have been a place of reason and science. Instead, the man’s rotting corpse is worshipped as a god and the people who spread and police this religion are the Eccelesiarchy, a cabal of foaming-at-the-mouth fanatics who punish heresy with death.
As the military arm of the Ecclesiarchy this fanaticism infects the Sisters of Battle, and while fervent in their faith Ideological purity does not equal morality. As their history shows the Sisters are one charismatic lunatic away from turning against the Imperium, and if they do all would be considered heretics – including ordinary citizens – and all would be purged. And that's bad news, because the Sisters can go toe-to-toe with Space Marines.
They may be the coolest army on the table but they are dangerously unstable, walking the razor’s edge between crusader and terrorist, and with the Ecclesiarchy being as aggressively and fanatically oppressive as it is, the Sisters lean far more to the side of evil than good. As said by Canonness Sabine: ‘These heretics refute the Emperor’s holy right to rule. Let them argue with the barrel of a gun.’