“murder is wrong” is a moral absolute if you adopt the deontological viewpoint. It’s not if you adopt the teleological approach. Discussing these things is literally what I learnt in the very short Ethics course I had in third year uni (while in France that sort of stuff was much much earlier during Philosophy class…)

Edit : and to be clear, I think absolute opinions are the province of the philosopher and the fanatic. Real life tends to be a bit more messy. But that’s why it’s important to sort of know what the options are and how difficult the choices can be (again, for real human beings who struggle with dilemmas ; fanatics tend to eachew all that and I’d say that’s how you can spot them).