They’re certainly doing something wrong from our perspective, and indeed, the Nazis were even doing evil things from their own perspective, which is why they put so much effort in the dying days of the war into concealing what they had been up to.
But even look at the Church, burning poor old Giordano Bruno alive for the crime of practicing his apparently universal liberties… Except of course that concept didn’t actual exist in Bruno’s time.
Of course, I get the uncomfortable feeling that a few people out there wish heretics and blasphemers could still be “dealt with”, so I’m not sure the entirety of Christendom is convinced punishing for denying the Trinity is actually wrong, even if they think lighting a fire under them isn’t the best way to prosecute such a vile crime.