Clive Staples Lewis was Professor of Medieval and Renaissance Literature at Cambridge University, Fellow in English at Oxford University’s Magdalen College, and the author of the series of children’s classics The Chronicles of Narnia. Following his conversion from atheism to Christianity, described in his autobiography Surprised by Joy, he was both a popular and a prolific Christian apologist.

Mere Christianity

Lewis’s most famous apologetic work is Mere Christianity. This work began life as a series of 15-minute radio broadcasts prepared for the BBC, but those broadcasts were subsequently published in print. The premise of the work was to explore the fundamentals of Christian faith—what do Christians believe, and why?—without entering into complicated inter-denominational squabbles about minor doctrine.

Mere Christianity is best known, however, for its opening chapters, in which Lewis sets out his version of the moral argument, explaining why our sense of right and wrong implies the existence of both an objective morality and of a legislator of that objective morality. This is widely acclaimed as apologetics at its best: plausible at every step, quickly building a compelling case for faith.

Also in Mere Christianity is Lewis’s Lord / liar / lunatic trilemma, which challenges those that deem Jesus a great human being, an inspirational moral teacher, but nothing more. Given the claims that Jesus made about himself, Lewis argues, for example his claims to have authority to forgive sins, we cannot take this position. If those claims were false, then we should denounce Jesus as either a lunatic (if he believed them) or a liar (if he did not). If they were true, we should recognise that Jesus was far more than a great teacher, and acknowledge him as Lord.

The Screwtape Letters

Another firm favourite of Lewis fans is his satire The Screwtape Letters, a brilliant (and humorous) collection of letters of advice written by the demon Screwtape to his apprentice and nephew Wormwood. Wormwood is struggling to disrupt the faith of the man to whom he has been assigned, his “patient”; Screwtape advises him on what techniques to use. Through this device, Lewis advises Christians on what schemes of demons to guard against.

The Pilgrim’s Regress

The Pilgrim’s Regress is Lewis’s first novel, an allegorical tale inspired by John Bunyan’s Pilgrim’s Progress. In it, John, having had a vision of a beautiful island, sets out from the land of Puritania to find it. As he goes, he meets strange characters, caricatures of major worldviews: Sigismund Enlightenment, Media Halfways, and Mother Kirk, et. al. Appreciation of this work does require some background knowledge, without which many references will be missed, and this has diminished its popularity. Underlying the allegory is autobiography; John’s journey is much like Lewis’s own, from the empty churchgoing of his childhood, through atheism, to ‘Joy‘.

The Problem of Pain

The Problem of Pain is Lewis’s response to the problem of evil. The book begins with Lewis looking back at the response he would have given if asked “Why do you not believe in God?” when an atheist.

He first surveys the arrangement of nature, and the constant association of life with pain: “The creatures cause pain by being born, and live by inflicting pain, and in pain they mostly die.”

He then considers the impact of reason, which “enables men by a hundred ingenious contrivances to inflict a great deal more pain than they otherwise could have done on one another and on the irrational creatures. This power they have exploited to the full.”

The pre-Christian Lewis concludes, “If you ask me to believe that this is the work of a benevolent and omnipotent spirit, I reply that all the evidence points in the opposite direction. Either there is no spirit behind the universe, or else a spirit indifferent to good and evil, or else an evil spirit.”

In The Problem of Pain, Lewis the Christian apologist replies to Lewis the atheist, exploring what is meant by divine power and divine love, and the greater purpose of pain.


Every experience of the supernatural is just that: an experience. Experiences are, though, by their very nature, subjective; it is always possible to question an experience; there is always room for doubt. How, then, can we ever trust an experience of the miraculous? What are we to do when our senses clash with our reason, when we seem to experience what we do not believe can occur? Miracles is Lewis’s response to this problem, his case for believing in both the possibility and the actuality of divine intervention in the world.

The Abolition of Man

Superficially a set of three essays on education—“Men Without Chests”, “The Way”, and “The Abolition of Man”—this collection is of much broader interest than that. It is, in fact, a concise, snappy treatment of subjectivism, and even scepticism, in ethics, and their dire consequences. Lewis defends the idea that there is an eternal and immutable moral law that, no matter how much we attempt to reduce it personal preferences and cultural attitudes, cannot be conquered.

The Great Divorce

A second work dealing with subjectivism, this time religious rather than ethical subjectivism, is The Great Divorce. The style is in many ways similar to The Pilgrim’s Regress. This work, which gets its title from William Blake’s The Marriage Between Heaven and Hell, follows the narrator on a bus journey to both. Using this device, Lewis seeks to debunk the universalist idea that all are saved, that whatever path one chooses for one’s life will ultimately fulfil the same role as any other and so will lead to the same place.

The Four Loves

The Greek language in which the New Testament was written has four words for love, each meaning something slightly different: storge (affection), philia (friendship), eros (romantic love), and agape (charity). In The Four Loves Lewis explores each of them, how they differ, and how they relate. He sees the first three as natural loves, but the fourth as the gift of God, without which the other three can become distorted.