Of all the grating arguments I hear from sanctimonious Christians, perhaps the most irritating is that, without some sort of religious grounding (translation: theirs), one simply cannot have any moral foundation for life.
These folks will whine on about moral "relativism" and claim that one can't lay claim to any sort of "morality" without a pre-written code of moral absolutes of some kind, at which point they will smugly whip out a copy of the Ten Commandments as if that somehow clinches the argument. So for all those wanks, I have a simple thought experiment.
Let's consider the Ten Commandments, then, shall we? (And which set would that be? Oh, let's not get into that, it would just make this more complicated than it has to be.) And let's consider that "don't commit adultery" admonition.
According to the wankish devout, adultery is clearly a bad thing, and they would have no problem pointing to the moral absolutes of the Commandments to back them up. Fair enough. But what if the situation changed?
Let's imagine that a stunning archeological discovery proved, beyond any doubt, that the universally-accepted Commandments had been transcribed incorrectly; specifically, that that aforementioned commandment really should have read "Thou shalt commit adultery." (And, please, don't argue with me about how unlikely this is -- that's why it's called a "thought experiment." Deal with it.)
So ... this new evidence comes to light and Biblical scholars the world over accept the overwhelming evidence that, yes, they've been wrong all this time. What happens to the argument from moral absolutes? More to the point, what happens to the moral absolutist? Well, there really are only two choices, aren't there?
If the absolutist changes his or her opinion to mesh with the evidence, well, that means that what had been an unshakeable moral "absolute" all this time was no such thing. For years, the absolutist would have been adamant that adultery was "wrong," but that same person now happily flip flops completely, which makes it clear that what was once "absolute" is now totally arbitrary. So much for absolutes.
But what if the absolutist refuses to go along, and sticks by her position that adultery is wrong, no matter what the new evidence suggests? If that's the case, then she has openly admitted that there is such a thing as morality quite independent of Scripture, no? Which is precisely what she's been denying all these years.
In short, this is a no-win situation for the absolutist, isn't it? Damned if you do, damned it you don't. But I mean that in a strictly rhetorical way, of course.
BY THE WAY, the above example of changing morals in mid-stream is not as far-fetched as you'd like to think. In fact, it happens frequently as you pass from the Old Testament to the New Testament.
Consider Matthew 5:38-39:
You have heard that it was said, 'Eye for eye, and tooth for tooth.' But I [Jesus] tell you, Do not resist an evil person. If someone strikes you on the right cheek, turn to him the other also.
Now isn't that a major about face when it comes to the concept of justice? When Jesus himself rewrites the rules for retribution before your very eyes, it's safe to say that the entire Scriptural concept of morality is more than a little malleable.