Christians murdering...?

ok so i was thinking today how christians like to say there right all the time like most religions. so was it right for the christians to kill the people accused of being witches? or the indians cuz they didnt wanna follow there beliefs? or how bout the kkk with the black people? $hit the kkk would burn a cross what does that even mean?....... so my question is what is everones thoughts on these tragic events of the past. like do you think they were in the right? or wrong and why?