I'd argue that we don't,though we'd have to be careful how we define the terms. Some things, like the Holocaust, we can claim are absolutely wrong in terms of contemporary morality, but the Old Testament records tales of mass murder and genocide and what we'd now call ethnic cleansing, some of them done directly by the deity himself, and all of them done with at least his approval and connivance. There's no hint in Scripture that any of them were in any sense a bad thing. Modern ethics would also say that slavery is absolutely wrong, but neither the Bible nor the Quran suggest any such thing, they offer nothing but acceptance of the institution of slavery. Not even Jesus himself, who had plenty of opportunities to speak out against it, is reported as disapproving of it. Morality is relative to the societies that define it, and things can be defined as unreservedly bad in those terms, but in truly absolute terms, it doesn't work. I've been thinking about this question since this thread, and some related ones, started, and I've been asking myself, is there something that every culture in history that we know about has defined as absolutely wrong. It may be just a function of my lack of historical knowledge--I'm an engineer, not a historian--but I couldn't come up with anything. Not even murder. Even our own supposedly ethically advanced culture recognizes self-defense as a legitimate justification for it. Is there something in the category of absolute wrong in all societies in all times and places? I haven't been able to think of anything.
