The attempt to excuse the Inquisition as less evil (by numeric count) than communisiom is amusing. It ignores the question of what a religion founded by Jesus was doing murdering and torturing people, and it ignores the question of why the religion itself didn't prevent it from happening.
Obviously theocracies can be evil, regardless of the nominal religion they spring from.
You asked and answered your own question. By definition, a non-coercive religion cannot "prevent" theocracies.
What do you mean by a non-coersive religion? I would say that a religion that threatens eternal punishment for incorrect beliefs is being coersive.