True, but some "objective" moral values do exist. Virtually no culture allows random murder or theft. In fact many anthropologists agree that there are a couple of core values almost every culture has. However, this does not really do the pro-God side any good, as one could also argue that it's a survival mechanism. We don't allow random murder, because we don't want to be murdered ourselves.
Actually, I think it does, because there is a difference between something that is socially unacceptable because it decreases chances of survival, like putting your own house on fire, and something that is really
morally wrong, like rape. Of course, rape can also have negative effects on the chances of survival, but if it was not accepted by society only because of that, it would be considered taboo only, and not per se morally wrong. (this is basically what William L. Craig said)
I'm still undeciced on the morality argument tbh, and I don't think any of us in here are in a position to make a quick judgement about it. I mean, to say like Martin that a guy who has studied philosophy and theology at the highest academic level for more than 20 years, comes up with an argument 'out of the blue', just sounds too harsh, and - ironically- out of the blue.