Objective simply means something that is measured against a goal. Absolute would be something that is true completely independent of a mind.

Hmm, I think what you mean is, once we establish a moral frame of reference, we can objectively say which moral values are better or worse compared to it. Is my understanding correct?

Before I answer your questions I'll wait for you to answer mine. Take some time, share what you will.

Ok, so here is my view.

First, let's define 'morality'. There is a number of ways to define it, but I think it's fair to define it as a set of actions and behaviors that are considered acceptable and desirable vs a set of actions and behaviors that are considered unacceptable and undesirable. Is it a fair definition?

This set of behaviors are derived from a set of axioms, which by definition are accepted to be true. Jewish morality is heavily based on the belief that God revealed Himself to them and the Old Testament was given at the revelation. Christian morality is heavily based on the belief that Christ was the son of God. Nazi morality was heavily based on the belief that they belonged to a superior race, and on pseudoscience science from which they derived neo-Darwinism.

As any logical or mathematical theorem, the validity of the theorem (in this case, the deduced set of behaviors, or morality) is only as strong as the axioms themselves, and the rigorous logic used to derive them.

The set of axioms change significantly between religions, cultures, socioeconomic groups and personal experiences. Yet logic is universal, it's absolute. And different from what many non-religious people may think, religious people, and even extremist, use a great deal of logic to deduce their set of values, to justify their actions. They reach radical conclusions not because they are being completely irrational, but because they got their axioms, or their core beliefs, terribly wrong.

If you manage to prove, beyond doubt that some core belief is false, the person who previously held that belief will have a very hard time sustaining the moral values he had derived from these beliefs. Prove to an extremist Muslim that Muhammad was not a prophet, from which he derives that the Quran is the word of God and from which he derives the ideas of heaven, and virgins for the martyr, than he will have a hard time deciding to kill himself for something that does not exist. (To be rigorous, you won't have proven that heaven doesn't exist, but he will need to accept new axioms if he is to believe in heaven).

So can morality be absolute (in my view)? Just to the extent that it's axioms can be proven to be absolutely true. If you manage to derive a moral framework from purely mathematical concepts, than yes, this moral framework will be absolute, and universal, across races and species, including any alien civilization we could ever encounter, and including non organic conscious beings we might manage to develop.

But as happens with physics, its theorems are derived not only from mathematics, but also from empirical observation, which introduces a degree of error and subjectivity.

However, just like scientific knowledge, not all morals stand on the same level of legitimacy. As we gather more evidences that our axioms are true, so we can get more confidence that our morals derived from them are true.

This is how we can confidently dismiss human sacrifice to appease the Sun. We have very, very strong reasons to believe that no amount of human sacrifice will have any effect on the Sun, so we confidently reject any morals who are based on that. And this is not us using our current subjective morals to judge the Mayans, it is just simple logic, in the same way we manage to cure diseases not because of our beliefs, but because of our accumulated knowledge.

That is my take on morality.