Jim Farmelant: Well, I would go further and argue that not even religion can ground morality even if we do posit the existence of gods because that would take us into the famous Euthyphro Problem which was first outlined in Plato's dialog with that name (see: http://classics.mit.edu/Plato/euthyfro.html
I'm an atheist, but my focus is political -- and I see no point (other than for occasional entertainment of all involved) to debate metaphysics with those on the side of resistance.
Carrol