As I see it, the catch-22 with any kind of statement which denies absolutes is that, that denying statement becomes itself the first absolute.
I see values and morals as intertwined. If I value human life, then it is immoral to kill. If I value relativism--there are no moral absolutes--then this becomes my absolute.
I suppose that many people see morals/values and religion/God as intertwined. Thus, if there is no God (or at least, no certainty that he exists), then there is no certain base from which absolute morals come.
I don't see this God-morals connection as necessary. IMO, there are absolutes in the mental-symbolic sphere (eg, If a=b and b=c then a=c; a self-defining absolute), just as there are absolutes in the physical-sensory sphere (physical constants in our type of universe, which make our universe the type it is).
We've had this discussion before, because I've posted this reasoning before.
I would also argue that moral absolutes can be highlighted from an evolutionary point of view: those values which enable a group of people to survive and prosper; and heck, who doesn't wanna survive and prosper (wouldn't that be an absolute hard-wired into human being)? I would think that any society which tests its weapons on its own people would do neither, or at best, do so short-term compared to a society which tests its weapons on other people. 馃槈
IMO, absolute "moral relativism" smacks of mind thinking itself "enlightened" and free of all cultural shackles from the past. "We've learned from past mistakes." It implies some kinda pinnacle of moral development; and considering that homo sapiens have been around for only 150,000 years--large societies for only about 5,000 years--I respectfully submit that this is likely not the case.
Thanks for listening.