If one cannot know The Truth, then how can one know right or wrong? Such is the age-old battle between moral absolutism and moral relativism.
Moral absolutism is based on the concept of an “objective morality” that applies equally to everyone. The problem with this, of course, is that it is impossible to defend an objective viewpoint when it is based on a subjective interpretation. If my absolute theology differs from your absolute theology, who is right? Usually, the one with the biggest army.
Moral relativism, on the other hand, is based on the concept that, since “objective morality” might be too big to comprehend, then it is ok to have conflicting viewpoints. Much like the parable of the blind men and the elephant, we can all simultaneously be right and wrong. The problem with this, of course, is that when taken to the extreme, moral relativism can be used to justify all sorts of horrific actions. Since the objective morality can never be understood, then the subjective morality can be whatever I want it to be.
It should be noted that moral absolutism has been used to justify many horrific actions, too. So, in this case, neither is really superior to the other. That being said, which is right? Is there an objective morality, even if it is too big for a single person to comprehend? An elephant, after all, is an elephant, whether the blind men can agree or not.
If one cannot comprehend The Truth, then one can seek out someone or something that can. And, in this case, that something might be the collective intelligence of the human race. As blind individuals, we might not be able to comprehend the totality of the elephant, but collectively we can share notes and figure it out. As individuals, we might not be able to comprehend The Truth, but collectively we can work something out.
Which leads me back to the subject of absolute vs. relative morality. If there is an objective morality that applies to everyone, then it exists where our various theologies intersect. Thus, for example, nearly all societies collectively believe that murder is wrong. To murder thy neighbor is a wrong thing to do. But what about murder in self-defense? If your neighbor is trying to murder you, but you manage to murder him first, is that wrong? Some would say no, that you have a right to defend yourself. Some would say yes, that murder is murder, no matter what. But most would say yes, murder is murder, but the wrongness is subordinate to the greater rightness of survival. Therefore, the collective morality at work: murder is wrong, but the right to survive is greater. There may be consequences for murder even in self-defense (a trial by peers), but the consequences will be less severe than outright murder.
So, the point I am trying to make is that perhaps objective morality, if it exists, lies in the examination of all theologies, and not in the total rejection of all theologies, or the perpetuation of any single one. You can use the objective methods of science to compare theologies; comparative mythologists have been doing so for many years.
Anyone who looks around understands that the universe is much bigger than us. Perhaps we should start sharing notes instead of fighting about it.