But one must define morality first to see what those large parts that are absolute and relative. It is important to note that morality can be very different from culture to culture...One culture can believe that adultery is moral and murder is immoral, while another culture may view both adultery and murder as immoral.
Is a morality based on the Ten Commandments Absolute or Relative and does it make a difference if you are a Christian or not? If one is a true Christian, then these must be absolute.
You shall have no other gods before Me.
You shall not make idols.
You shall not take the name of the LORD your God in vain.
Remember the Sabbath day, to keep it holy.
Honor your father and your mother.
You shall not murder.
You shall not commit adultery.
You shall not steal.
You shall not bear false witness against your neighbor.
You shall not covet.
One could argue that the last four are far more absolute, and the first six may be relative.
We all know that in every culture, murder is bad (and I recognize that how murder is defined is important)...in any scenario worldwide across cultures, the wanton killing of other human beings for no justifiable reason (and yes, again, the definition of "justification" would have a huge impact on this discussion) would be considered immoral. I cannot think of any culture where one member of a people/tribe/society can snuff another person, any person (of their same people/tribe/society randomly for no reason, and not provoke.
Same with stealing. People from every point in history, and every place in time who were thieves are considered immoral by the societies they live in, so it is more absolute (objective) than relative (subjective)
But there are other facets that do cleave sharply across cultures and religions.
As for free will:
PRIEST: "Choice! The boy has no real choice, has he? Self interest, fear of physical pain drove him to that grotesque act of self abasement. Its insincerity was clearly to be seen. He ceases also to be a creature capable of moral choice."
(I just saw this movie again last night, so...it stuck in my brain! Basically, if deprived of your free will, can you be moral?