I've read/heard before that agitating and anxiety-induced chatter about how "without God we will have no moral ground" etc., and I've read/heard atheists and agnostics skewer it as though it rendered Christian commitment ethically vacuous (claiming that (A) if anyone does that, they're not thinking or acting morally, that (B) religious folks in fact borrow their morality from somewhere else and that (C) if (B), that this shows that the argument that "only a god (even God) can secure/provide our moral verities" is both false and insincere). It's not really difficult to refute it.
I guess it just strikes me as a bizarre (and Modern) argument, and at variance with both the Church's traditional approach to/understanding of the relation between common ethical precepts and intuitions and the Church's ascetical teachings on one hand, and the general sensibilities of the actually religious that I know on the other hand, whether Jews, Christians, Sikh, or Hindu of various sorts (I live in New England, so this may be a demographic peculiarity).
It seems to me that moral intuitions are common to all of us, and that we each and all have a conscience (or almost all of us, the overwhelming majority), not just the religious. It becomes more acute through training, consciously moral choices or through neuroses. It can get dull through the same (substituting "amoral" for "moral" in the choices). It strikes me that this common feature of our humanity will be interpreted by religious folks -- or let's keep it more specific, traditional Christians, Orthodox and Roman Catholic -- one way (who may then say that their ethical commitments are clarified and strengthened by religious experiences, and who thus perceive and interpret all ethical intuitions as having God, as the Good, as their proper end), and by agnostics and atheists another way (a pragmatic consideration, empathy, selfish interest, an evolutionary "program," mere convention, etc.).
I dunno, I'm just a guy with a keyboard, but it seems to me that this ambiguity is where our attention should go, and that we shouldn't waste it on those who make claims like "God (or Religion, or the Bible, or whatever) is what morality is based on." I was actually surprised to read that someone I respect, who is much more intelligent and cultured than I, was citing this claim seriously, even if it was only as a mirror to reveal other political postures as like unto it.
I am surprised by how often I've heard this claim refuted recently. I don't ever really hear it advanced, though I know some people do. It strikes me as a fundamentally eccentric claim.