C.S. Lewis and the “Romantic Heresy”

by Jeffrey Barbeau

Among the most well-known books in English in the twentieth century, first published as a single text in 1952, Mere Christianity began as a series of radio talks between 1942 and 1945. Yet this renowned work displays precisely the sort of emotive rhetoric that leads some to ponder Lewis’s method.

Notice the opening line of his opening talk: “Every one has heard people quarrelling” (C. S. Lewis, Mere Christianity [New York: HarperOne, 2000], 1). Lewis begins in a rather strange place for a series of lectures on “Right and Wrong as a Clue to the Meaning of the Universe.” The chapter, titled “The Law of Human Nature,” resonates with readers because Lewis begins precisely with that which some of Lewis’s contemporaries would rather he exclude, namely, individual human experience. Instead of identifying a philosophical principle of the good or the true, Lewis starts with the familiar occurrence of arguing with another person. Not only has everyone heard others engaged in such verbal bouts, but everyone also has participated in just such brawls. “It’s my turn, not yours!” “You wouldn’t like it if I broke your favorite mug!” “Didn’t we agree to clean this up together?”

Lewis’s purpose in drawing his readers’ attention to such language is to demonstrate the existence of a law that is shared by all people, in all places, at all times. Lewis’s moral canon works precisely because it is not only known by all intellectually but also felt by all personally. His examples thereby serve as reminders of a connection between what we sometimes call the subjective and objective. Note well: Lewis does not begin with the affirmation of a knowledge taught only in the Scriptures and available to a few but with an appeal to a universal experience of individual morality (whatever exceptions might be found in the population as a whole).

Notice, too, that Lewis makes clear that the law of human nature is not the same as something so unswerving and unalterable as the law of gravitation (Lewis, Mere Christianity, 20). This is neither a fact of nature—such that humans must always and necessarily behave in a particular manner—nor some inventive fancy. Human nature is the result of neither intellection nor appetite. The law of right and wrong results from some third aspect that dictates human behavior: “a moral law, which they did not make, and cannot quite forget even when they try” (Lewis, Mere Christianity, 23).

Lewis later identifies this sense of the moral law as conscience. For Lewis, the notion implies both a consciousness of something within human nature and a someone “inside ourselves as an influence or a command trying to get us to behave in a certain way” (Lewis, Mere Christianity, 24). Here, at the crossroads of a law we feel compelled to meet and a mind behind that law we know we ought to obey, Lewis grounds his case for the personal God described by Christianity.

The question I wish to ask is why Lewis begins his case for Christianity with an appeal to personal experience. And I think an additional question that might be posed is why his defense of Christianity was so successful among his listeners and readers. The answer to these questions, I suspect, lies in several different but related movements within modern thought—movements that I think Lewis was more aware of than some scholars admit.

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Adapted from The Last Romantic by Jeffrey W. Barbeau. ©2025 Jeffrey W. Barbeau. Used by permission of InterVarsity Press. www.ivpress.com.