Moral justification isn't necessary in the absence of immorality. Burning witches was not considered immoral for a period of time in history. Accusations of witchcraft resulted in court-ordered death. That does not happen today. Something has obviously changed. Aside from knowing that witchcraft is bullshit, we've also somehow arrived at a point where we now say that killing someone based solely on an accusation is wrong.
It's entirely disingenuous to suggest that the perspective of what is moral and immoral today is the same perspective that people had a couple hundred years ago or a couple thousand year ago. Time in history and culture dominate moral appraisals, most commonly in the form of what is considered immoral.
Your argument is kind of self defeating. If morals were subject to periodical contexts we couldn't even say that these actions are wrong. I'm fairly sure you're using this witch burning example for that very reason: it's abominable and you know the contrast is startling.
Are you willing to say the you would be agreeably involved in such a thing because it was the local flavor? You wouldn't recognize right from wrong? Would you be wearing a white hood and burning crosses 100 years ago?
And in reality, in the family of man, very little has changed. Only the players. Homosexuals are tossed of off roofs, farmers are robbed and starved out; genocide still occurs presently and look. it's today, in our historical moment of enlightenment. And they're all morally reprehensible, no matter what excuse the actors cite.
Morals are absolute. We know this. We're just creative enough to distort the lens in order to find justification for our immorality.
