Here are a couple of questions for anyone who embraces a naturalistic worldview and also believes that there's an objective right and wrong independent of any transcendent moral authority (i.e. God):
In Woody Allen's 1989 film Crimes and Misdemeanors, successful opthamologist Judah Rosenthal (Martin Landau) is cheating on his wife with a woman named Delores (Angelica Huston). Delores wants Judah to leave his wife, Miriam (Claire Bloom), for her, but Judah is unwilling, so Delores threatens to tell his wife all about their affair.
This would essentially ruin Judah's life, but Delores follows through with a letter to Miriam explaining the relationship she's had with Judah. Judah, however, discovers the letter before Miriam sees it, and it throws him into a panic. His life is about to come crashing down, and he doesn't know what to do to stop it.
He confides in his brother, Jack, who has underworld connections, and Jack suggests having Delores murdered. Judah is reluctant at first, but he eventually can see no other way out. Delores, who has no family, is killed, and although Judah is terrified that he'll be implicated, he eventually realizes to his great relief that he has gotten away with the crime. Nothing ties him or anyone else to the homicide.
No one knows what has actually happened except his brother and him, and he's able to live "happily ever after."
My questions are these: Is what Judah Rosenthal did morally wrong (as opposed to illegal)? If so, why is it wrong? Assuming a Godless universe in which Judah gets away with the crime, what does it mean to say that murder is wrong?
No one can be consistent who says on the one hand that there is no God and on the other that it was a moral outrage to murder that woman. Yet almost everyone but a psychopath has a visceral certainty that what was done to Delores was wrong which means that to be a consistent atheist most people have to somehow deny what they're certain is true.
This is an untenable predicament. To be rational an atheist has to either give up her atheism or give up what she's certain is true. It's astonishing, to me, at least, that so many would prefer the latter course of action to the former.