One of my MCCC philosophy students recently told me this:
"I do not believe in God, but I am not an atheist. I believe in morality."
"Then you are an atheist. And, on atheism morality (of the objective, binding, adjudicating kind) does not exist."
This student's belief in morality, with moral claims such as Racism is wrong, should make them consider theism. The theistic worldview provides a sufficient metaphysical foundation for objective moral values and duties. Which means: morality makes sense on the worldview of theism; morality does not make sense on the worldview of atheism as philosophical naturalism.
Given philosophical naturalism, objective values are at most epiphenomena. Because "value" does not inhere in matter.
Note that this does not mean atheists cannot act morally. Indeed, many of them do. But, following Nietzsche, they are like those village atheists who have co-opted Christian theistic morality into their professed atheism. In this they are irrational.
If there is an all-loving God, then objective moral values would find their warrant in the commands of such a God. This is to say that objective (= binding on all persons) moral values find their warrant in the being of God. This would provide a metaphysical grounding for morality, and thus there would be actions that are really wrong, objectively. But if atheism is true then the moral impulse is absurd (see here especially the atheistic existentialists such as Sartre).
I can't help but think of C.S. Lewis's idea that "Right and Wrong are clues to the meaning of the universe." Lewis writes:
"These, then, are the two points I wanted to make. First, that human beings, all over the earth, have this curious idea that they ought to behave in a certain way, and cannot really get rid of it. Secondly, that they do not in fact behave in that way. They know the Law of Nature; they break it. These two facts are the foundation of all clear thinking about ourselves and the universe we live in." Lewis, C. S. (2009-05-28). Mere Christianity (p. 8). Harper Collins, Inc.. Kindle Edition.
Many intellectual atheists understand what I have written above. Here's a sampling.
The existentialist, on the contrary, finds it extremely embarrassing that God does not exist, for there disappears with Him all possibility of finding values in an intelligible heaven. There can no longer be any good a priori, since there is no infinite and perfect consciousness to think it. It is nowhere written that 'the good' exists, that one must be honest or must not lie, since we are now upon the plane where there are only men. Dostoevsky once wrote: 'If God did not exist, everything would be permitted'; and that, for existentialism, is the starting point. Everything is indeed permitted if God does not exist, and man is in consequence forlorn, for he cannot find anything to depend upon either within or outside himself."
- Jean-Paul Sartre, Existentialism Is a Humanism, 28
"The central question about moral and ethical principles concerns their ontological foundation. If they are neither derived from God nor anchored in some transcendent ground, they are purely ephemeral."
- Paul Kurtz, Forbidden Fruit: the Ethics of Secularism, 65
"If there is no single moral authority [i.e. no God] we have to in some sense 'create' values for ourselves ... [and] that means that moral claims are not true or false… you may disagree with me but you cannot say I have made a factual error."
- Julian Baggini, Atheism: A Very Short Introduction, cf. pp. 41-51
"The universe that we observe has precisely the properties we should expect if there is, at bottom, no design, no purpose [i.e. no God], no evil, no good, nothing but pitiless indifference." ( ‘God’s Utility Function’, Scientific American, November 1995, p.85) Dawkins concedes: "It is pretty hard to defend absolutist morals on grounds other than religious ones."( The God Delusion, p.232)