They probably didn’t think they were evil.
The Khmer Rouge probably didn’t think they were evil ...
The Viet Cong probably didn’t think they were evil ...
The Sendero Luminoso probably didn’t think they were evil ...
The Red Brigades probably didn’t think they were evil ...
The Moro Islamic Liberation Front probably doesn’t think it’s evil ...
To a moral relativist, that’s probably all that matters.