For what statement to have absolute meaning? Why do we need an absolute definition of "badness"?
That's an excellent question, why do we *need* absolute morality? I don't claim great wisdom, but one use for absolute morality might be to avoid confusion as well as mediate between self-interested parties with competing definitions of morality. As you touched on, perhaps this helps lead people to a higher degree of "good" that wouldn't have been obvious to all parties.
Within argument, I think we need absolute definitions inasmuch as we want to make absolute statements such as: X is always true. I assume atheists are making absolute statements when they make arguments against God, but perhaps all they really mean is, "For all I can see, there is no God." If that is the case, I would be interested to know, because making such a definitive statement would require a certain amount of omniscience attributed only to you-know-who (not Lord Voldemort).
Even people within the same culture won't agree on what's good and bad.
I was merely assuming a definition of "meaningful." In truth I fully agree with you that people disagree all over the place and am not trying to demonstrate God exists by saying "everyone agrees on morality." They don't. They do tend to agree there is such a thing as morality, just not what it is in particular.
My definition of absolute morality; however, is based on what God considers "good" or "evil", not as we prefer it. I readily admit though that understanding what God precisely means by righteousness takes up the better half of religious study, and failure to understand Him (or listen) has resulted in people doing dastardly things in His name.
Sorry I don't write more clearly. I just mean it can't be used as a proof. In any case, thank you for the thoughtful response.