Nietzsche didn't believe in universal ethics/morality. He b…

Nietzsche didn't believe in universal ethics/morality. He believed in might is right, as any consistent materialist does. From that perspective it's not about good/evil, but about "good for me/us" "bad for me/us". Enslaving people is good when we do it, but bad if they do it to us. It's all perspective, moral relativism. Christianity on the other hand, and I say that as someone who can’t claim to be a Christian, has probably done more against slavery than anything else in history by proclaiming that every human being has value (and therefore individual rights). Christianity has, of course, been corrupted by power and it certainly didn't always deliver what it promised, but without it slavery would probably be as common today as it was in Rome or Babylon.