The conscience is a dilemma for the believer in evolution. He doesn't know why it exists. Neither do the experts. Why would evolution create something that tells us that it's wrong to lie, to steal, to kill, and to commit adultery? Was primitive man committing these sins before he evolved a conscience? If he wasn't, why didn't his conscience evolve? If he was, why did the conscience evolve?

You Can Lead an Atheist to Evidence, But You Can't Make Him Think (2009)