I think there is an argument to be made for moral relativity within the context of culture and time. Stoning a woman to death for adultery would surely be regarded as immoral today but not 5000 years ago. When Aztec priests ripped the heart out young girls in a sacrifice to their god a thousand years ago it was consider not just moral but the ultimate virtuous act.I haven't read the thread, since it's 64 pages. But imo the question isn't whether atheists can be moral. The question should be, what is their morality grounded in? The real problem with atheism is that it has no solid basis for objective morality. That's why most atheists will say that morality is subjective, or relative. And I have yet to meet an atheist who is bright enough to understand that if morality is subjective, then it's ultimately meaningless, since no one morality can ever be better than any other.
That argument has been made, but I think there's a big misunderstanding there. Yes, cultural ideas on morality have changed over time, but it doesn't follow that the true nature of morality is relative or subjective. Adultery was wrong then and it's wrong now and it will always be wrong. (Regardless of what anyone believes.) The punishment for it has changed over time, as you brought up, but just because certain laws or customs are temporary doesn't mean that true (everlasting) morals and principles don't exist.
I hope that was clear.
You say adultery is wrong. But isn't it wrong to have married that person you don't love enough, in the first place?
Good point.
If talking serpents, talking donkeys, swine that do not ruminate, sheep, goats, wolves in sheep clothing etc., are metaphors for types of people then many well respected dedicated married religious folks are guilty of bestiality.