These questions are difficult to answer. I myself am undecided as to whether there is an absolute morality. Take poligomy, for example. If both parties are ok with it, is it really wrong? I have a hard time saying yes. Yet, I also acknowledge the the concept of someone having the right to an opinion as the standard when one hasn’t accepted an absolute morality is problematic to defend.
The best answer that I can come up, off the cuff is that morality being relative seems objective enough to me. If a group of people agree that xyz is important, then I think we can establish right and wrong.
That said, I tend to think basic morality isn’t relative (murder, theft, primarily) but I can’t say for certain. Generally speaking, morality can be deduced by applying the golden rule.
For the record, I am hardly an apologist for the agnostic view, even less for full on atheistic view. However, I am certain they have a much more reasoned arguments than what I gave you. I am merely talking out loud on many if these issues, because they are not altogether clear to me. I don’t see a slam dunk case. I see reasonable arguments on both sides.
I read this a while ago, but this would be the basic defense against the relativistic argument. I find the argument well reasoned, yet I am still undecided. Perhaps, because I know nothing in the end. Moral Relativity