Atheism is often criticized by Christians on the grounds that it does not provide any basis for morality. To these Christians, morality is a matter of following God's commands, and if there's no God to give this guidance, to establish values, then how can there by any morality?
In return, atheists often pointed out that obeying the literal commands of God (assuming that the literal commands of God are in fact recorded in the Bible) leads to some pretty horrific results, particularly if you look at the Old Testament. Are we really expected to stone adulterers to death? How can that possibly be a moral thing to do?
One answer I've often heard is that most of that Old Testament stuff no longer applies. Most recently, a Christian friend of mind argued that Jesus fulfilled the Levitican commandments (including the commandment to stone adulterers, but also the many kosher rules still observed by Jews today), and so they no longer need to be followed.
Okay, so that gets us off the hook for having to follow those old rules, and maybe the only obligations remaining are the ones that we all can feel nice and warm about, the ones that make moral sense to us today because they're rooted in the general principle, "love thy neighbour". And that's how I used to feel about the argument, until just after my friend brought it to my attention again, when it suddenly occurred to me that this doctrine creates greater problems than it solves.
Consider what it means for people living before Jesus came along to fulfil the commandments. It means that in those days, God wanted us to stone adulterers, and consequently that it was not just culturally acceptable, but morally right to do so! Something which, today, we consider morally outrageous and barbaric -- partially burying a living human being and then throwing rocks at the exposed parts until the person dies -- was good and proper at some time in the past. The very nature of morality has apparently changed.
I find this argument rather shocking, especially coming from a tradition that condemns moral relativism. I, too, have little patience with people who look at the various cultural practices going on today in other parts of the world, such as female genital mutilation and, yes, stoning adulterers to death, and say we can't judge it to be wrong because it's a different culture. Wrong is wrong, and just because something is culturally accepted somewhere doesn't make it right. I rather think it would go without saying that this is true across time as well as across space; if it's wrong to stone adulterers today, then it was wrong yesterday and wrong three thousand years ago. Conversely, if it was right three thousand years ago, it should be right today.
It also seems to me to be far more damaging to the idea of biblical literalism than even young-earth creationism. After all, there is something to the creationist rebuttal to scientific claims about origins: "Were you there? Did you see any of this?" No, of course, I wasn't there, and didn't see what happened with my own eyes, and it is conceivable that things unfolded differently from what modern science has inferred from the evidence. But claims about moral principles are different. I may not know the circumstances of any particular act of ancient adultery, but don't need to have lived 3000 years ago to say with great confidence that it would generally be wrong to stone someone to death for adultery. Wrong is wrong, and fundamental moral principles do not change over time, although our understanding of them certainly does evolve. Slavery was always wrong; it just took us a while collectively to recognize that.
I don't see a way out here for the theory that God's commandments are definitive of morality, or at least not one that also preserves the biblical literalism so many Christians insist upon (and which I've criticized as idolatrous (typo corrected Feb 13, 2012: I originally wrote "adulterous" by mistake) in an earlier post. You could say that the fundamental principles of morality are given by God, but encoded into the fabric of reality like the laws of physics or mathematics, rather than accurately described in the Bible, and that ethical philosophers like Kant, Mill, Jesus, Lao Tzu and Confucius have been adding to our understanding over time. Or you could just bite the bullet and insist that yes, the principles of morality really did change drastically when Jesus fulfilled the Levitican commandments, in which case it becomes rather puzzling to consider how Confucius came up with his version of the Golden Rule back in the days when the Golden rule couldn't possibly have applied because it really was morally right to stone people to death, to slaughter the Canaanites, and so on.