There is a common line of attack Christians use in debates with atheists, and I genuinely detest it. It’s to ask the question, “where do your morals come from?” I detest it because it is not a sincere question at all — they don’t care about your answer, they’re just trying to get you to say that you do not accept the authority of a deity, so that they can then declare that you are an evil person because you do not derive your morals from the same source they do, and therefore you are amoral. It is, of course, false to declare that someone with a different morality than yours is amoral, but that doesn’t stop those sleazebags.P. Z. Myers, “The “objective morality” gotcha” at Pharyngula/Free Thought blogs (September 22, 2012)
Actually, Christians don’t ask “Where do your morals come from?” in order to call atheists evil. We do it to point out that objective morality is powerful evidence for God’s existence.
How so? From our human perspective, moral law can have two origins — subjective and objective.
Subjective moral law is based on human opinion. It may just be one man’s opinion, or it may be the collective opinion of a group of people. If our standards are wholly subjective, dislike of strawberry ice cream and dislike of genocide are not qualitatively different. The dislike is just human opinion.
Objective moral law, by contrast, is outside of human opinion. It is something that we humans discover. We do not create it. Thus, objective moral law exists beyond mere human opinion.
Now a distinction emerges. Personal preferences (e.g., about ice cream) are qualitatively different from personal opinions about genocide — we oppose genocide because it is objectively wrong, not just because it is not quite to our taste.
Of course, if a value judgement prevails over other human value judgements, there must be Someone whose opinion is Objective Moral Law. There must be a Law-Giver. That is the one whom all men call God.
Please note that this argument is ontological, not epistemological. It is not an argument about how well we can know what the Moral Law is. It is an argument that Objective Moral Law exists, regardless of how well we can or do know it.
Of course, if all moral law were merely subjective human judgements, then meaningful arguments about right and wrong are impossible, because all morality is relative — we each create our own morality and no external objective standards exist. As Hume famously argued, you can’t get an ‘ought’ just from an ‘is’. My morals have the same validity yours do, so what is there to discuss? To what external moral standard can we appeal, if there are no external moral standards?
Myers, as you might expect, is a moral scold, which is odd, coming from an atheist who by definition denies any Source for objective moral standards. Without Objective Moral Law, debates about morality are merely assertions of power — I just try to force you to believe and act as I do because I assert the power to do so. And you do likewise to me.
Every time Myers scolds humanity on morality and immorality, he implicitly acknowledges God’s existence. Myers detests the question “where do your morals come from” because he can’t answer the question without acknowledging the existence of a non-human Moral Law-Giver. For an atheist, denying God’s existence appears to be more important than consistency, logic and evidence.
You may also wish to read: Faith in God is the only coherent basis for reason. Access to truth is always a matter of faith — the validity of reason cannot be validated by reason itself. Atheism provides no coherent warrant to trust the capacity for reason. In this sense, atheist faith is much more radical and less coherent than Christian faith.