The Existence of God 3/3: The Moral Argument

“You shall not murder” (Exodus 20:13).

Can we be good without God? The last argument for the existence of God I want to look at is the moral argument. It’s one that is frequently misunderstood by people on both sides, so we must tread carefully.

In On Guard, William Lane Craig describes the moral argument in this syllogism:

1. If God does not exist, objective moral values and duties do not exist.
2. Objective moral values and duties do exist.
3. Therefore, God exists.

This is a modus tollens form, and it is a valid argument — meaning, if the premises are true, the conclusion must be true as well. But are the premises true?

If God does not exist, objective morals do not exist? Why not? The real question is, how could they? What’s wrong with a lion killing a gazelle? What’s wrong with a bear killing a rival’s cubs? This is just the circle of life. This is survival of the fittest. So what’s wrong with a man killing a child? What’s the difference? If naturalism is true, we’re all just meat. Humans are merely slightly smarter animals. What makes them too special to kill? Though most atheists will not admit that the answer is “nothing,” some will. Darwin saw human morality as nothing but a product of evolution and not really binding. Sadly, those few who acknowledge this tend to take it to its logical conclusion, for example Peter Singer, who believes infanticide is less of an offense than killing a cow. If there is no God, then murder can be illegal, impolite, or inefficient, but it cannot be immoral.

Do objective moral values exist? Of course they do, and anyone who tells you otherwise will betray that notion the first time someone wrongs them. We don’t think murder or rape are merely impolite. They’re immoral. When someone is robbed, they are quite certain they’ve been wronged. And, deep down, everyone knows this. There is a moral code that runs through humanity. As C.S. Lewis put it,

“Think of a country where people were admired for running away in battle, or where a man felt proud of doublecrossing all the people who had been kindest to him. You might just as well try to imagine a country where two and two made five. Men have differed as regards what people you ought to be unselfish to -- whether it was only your own family, or your fellow countrymen, or everyone. But they have always agreed that you ought not to put yourself first. Selfishness has never been admired.”

If morals are just cultural or just a matter of opinion, Lewis says, there’d be “no sense in preferring ... Chrisitan morality to Nazi morality.” But we believe the Nazis were really, truly wrong. Why? How do we know that they are wrong? “A man does not call a line crooked unless he has some idea of a straight line.” We get that idea of a straight line, of the way things ought to be, from our creator.

Two objections must be dealt with. The first is the all too common misunderstanding of this argument as “atheists cannot be moral.” That is not what the argument says. We do not deny that atheists can behave morally. We do not deny that atheists can know what is and is not moral. We say that atheists cannot explain what “good” means. “Can we be good without God?” is the wrong question. The right question is “can there be good without God?” The answer is “no.”

The second objection says that some people are amoral, therefore everyone does not know what is moral, so the argument doesn’t work. But that’s not right. There are people who do not see anything wrong with killing or lying. There are also people who cannot see the color red. Defective people do not disprove the existence of the thing they are defective about. We know they are defective because of the experience of the vast majority of humanity.

So we’re left with the conclusion of our syllogism: God exists. There must be an external source for this moral information. If it only comes from inside us, it’s not real. If it’s as real as we all know it is, there’s only one explanation for how we all know it.

So what do we know about this God? From the first argument, he is eternal, immaterial, powerful, and personal. From the second, he is incredibly wise and desired human beings. From the third, we see that he is moral. We know there is right and wrong, and we know that we do wrong. How do we know that this God is the Christian God? The evidence that the Bible is divinely inspired shows us which god is God.

Is this all that we can know about this God? Not at all. He has chosen to reveal himself to us. And that is where we turn next.


For more on the moral argument, see Mere Christianity by C.S. Lewis.


Part of Christianity 101