Well, that figurative interpretation makes a strong case that the OP's theists are being morons and ignoring their bible when accusing atheists of having no morals. In this case I just found the literal interpretation to be amusing. The theists in this thread are helping to show that theists should never claim that we have no moral guidance. We DO have guidance according to Romans 2:14-15.
I would beg to differ though, I think our guidance comes from what we have been exposed to through our lives. Our morals, more or less, conform to the society in which we were raised and there are very few things that are true across all cultures. Off the top of my head, sex with relatives, and eating the dead are two morally reprehensible things that almost all cultures can agree on, but even those aren't true across literally all cultures.
I would beg to differ though, I think our guidance comes from what we have been exposed to through our lives. Our morals, more or less, conform to the society in which we were raised and there are very few things that are true across all cultures. Off the top of my head, sex with relatives, and eating the dead are two morally reprehensible things that almost all cultures can agree on, but even those aren't true across literally all cultures.