Mere Christianity by C.S. Lewis

Summary: Cotton candy apologetics – engaging and conversational but shallow.

The author of the popular Chronicles of Narnia series as well as several books on apologetics and theology, C.S. Lewis was an Oxford professor who claimed to have converted from Christianity to atheism and back to Christianity again. Mere Christianity is a revised and expanded version of three radio talks Lewis gave, and was written, as Lewis explains in the preface, to present the “mere” essence of Christianity; that is, to explain and defend the beliefs common to all Christian denominations. The first section, “Right and Wrong as a Clue to the Meaning of the Universe”, presents a version of the moral argument for the existence of God; the second section, “What Christians Believe”, explains the basics of Christian theology; the third, “Christian Behavior”, is a series of essays on various aspects of Christian life; and the final section, “Beyond Personality”, delves into the doctrines of the atonement and the Trinity.


Though the preface is only a lead-in to the rest of the book, it contains a very revealing statement. In explaining the purpose of the book, Lewis says that he is only writing to defend “mere” Christianity – the core of the religion, the beliefs common to all denominations – and that therefore this book will offer no help to someone who is already a Christian and is trying to decide between two denominations. Although Lewis admits that he is a member of the Church of England himself, he writes: “You will not learn from me whether you ought to become an Anglican, a Methodist, a Presbyterian, or a Roman Catholic” (

Lewis says that he will not discuss the differences in doctrine between the various Christian sects for two reasons: the first is that he does not feel qualified to write about the arcane points of theology that separate one denomination from another. But the second reason, he says, is this:

“And secondly, I think we must admit that the discussion of these disputed points has no tendency at all to bring an outsider into the Christian fold. So long as we write and talk about them we are much more likely to deter him from entering any Christian communion than to draw him into our own. Our divisions should never be discussed except in the presence of those who have already come to believe that there is one God and that Jesus Christ is His only Son” (

This is a very interesting – some would say damning – confession. Lewis claims that the doctrinal disputes between Christian sects are more likely to turn a seeker away than cause him to convert – and that therefore the appropriate response is to hide these disputes from people who are considering Christianity. How could such behavior be called anything other than deceptive?

If a person converts to Christianity because an evangelist has concealed from him some relevant fact that might have deterred him from converting had he known it in advance, then his conversion was made under false pretenses – it came about as the result of a lie. This would be comparable to a person who buys a house because its former owners failed to disclose that it was built on the site of a toxic waste dump. If Lewis is actually recommending that Christian evangelists practice this sort of dishonest behavior, what does this say about his own ethics? Keep this in mind as we consider Lewis’ moral argument for God’s existence, which is presented in the next section.


In this section, Lewis provides a version of the moral argument for the existence of God. His claim is that there is a universal moral standard, an unchanging sense of right and wrong, that runs throughout all cultures and all times. He points out that, when people denounce others’ behavior, they are usually not just saying that those others’ behavior does not please them; instead, they are appealing to some type of moral standard which they expect everyone to know about. He further claims that those accused of violating this standard rarely reject its existence outright, but almost always try to give some excuse as to why it does not apply to them in this particular situation. Lewis calls this standard the Law of Nature, and says that unlike physical laws such as gravity, which cannot be broken, humans are free to disobey it. Finally, he asserts that all human beings are constantly breaking this law, and appeals to his readers to recognize and admit their own culpability in this.

The point to which this is leading should be obvious: Lewis claims that only a supernatural power could have instilled this moral sense in us. He claims that the moral sense could not be just another human instinct, because it is never in complete agreement with any one instinct, but may encourage or discourage any of them based on the situation. “Now this thing that judges between two instincts, that decides which should be encouraged, cannot itself be either of them. You might as well say that the sheet of music which tells you, at a given moment, to play one note on the piano and not another, is itself one of the notes on the keyboard. The Moral Law tells us the tune we have to play: our instincts are merely the keys” (p.8). He also adds that the moral sense is usually in the position of encouraging the weaker, not the stronger, instinct. “The thing that tells you which note on the piano needs to be played louder cannot itself be that note” (p.9).

Lewis also dismisses claims that the moral sense could be simply a social convention, for two reasons. The first, he says, is because anyone who believes that human morality has ever improved (by the abolition of slavery, say, or the granting of voting rights to women) must necessarily believe that there is a standard, independent of what any particular society invents, which a given society’s morality can grow closer to or withdraw farther from. While this argument will not make much of an impression on moral relativists who do not, in fact, believe that human morality ever has improved in any objective sense, I am not a moral relativist, so I acknowledge that there is merit to this argument. However, Lewis goes too far in claiming that everyone will agree with it. “In fact, of course, we do all believe that some moralities are better than others” (p.11). He would do better to acknowledge that there are people who will not accept his argument rather than attempting to gloss over their existence.

However, it is with the second reason Lewis gives that the real problem arises. He claims that a common thread of values is recognizable running through every culture and every time, and presumably, that this is very unlikely if morality was simply a human invention. I will quote his presentation of this point in full:

“I know that some people say the idea of a Law of Nature or decent behaviour known to all men is unsound, because different civilisations and different ages have had quite different moralities.
        But this is not true. There have been differences between their moralities, but these have never amounted to anything like a total difference. If anyone will take the trouble to compare the moral teaching of, say, the ancient Egyptians, Babylonians, Hindus, Chinese, Greeks and Romans, what will really strike him will be how very like they are to each other and to our own” (p.5).

This breezy dismissal is astonishing. How can anyone claim with a straight face that all societies throughout history have had essentially the same moral code? Has Lewis never heard of Mormon and Arab polygamy, ancient Greek pedophilia and infanticide, Chinese foot-binding, Japanese ritual suicide, Aztec human sacrifice, African female genital mutilation, Islamic ritual murder (“honor killings”), terrorism and suicide bombings, medieval European totalitarian monarchy and inquisitions, Nazi eugenics and racism, even Christian-inspired slavery and colonialism, oppression of women, and anti-Semitism? Is he unaware that the Bible itself sanctions sexism, polygamy, slavery, discrimination against the handicapped, racism, holy war and genocide? While these things are looked on with horror by civilized societies today, at these times and places they were (and in some cases still are) moral norms that passed unchallenged. And that is not even to address the furious debates still going on today over the ethics of such issues as gay marriage, the ordination of homosexuals, abortion, euthanasia, capital punishment, sex education, drug legalization and the use of contraception. Clearly, all societies do not have the same moral law. The very few commonalities that can be found, such as prohibitions on murder and theft, do not need divine revelation to explain them; these laws are universal in human history precisely because any society that did not have them would soon collapse into chaos and would never enter history in the first place.

Lewis claims that most of the changes in societal morality that have come about are due to advances in factual knowledge, not different moral principles (e.g., the reason we no longer execute women as witches is because we no longer believe there are any such things, not because we believe people who gained powers from Satan in order to harm and kill others would not deserve it). But this is not true. There is no difference in factual knowledge that, for example, causes societies under Islamic sharia law to chop off the hands of thieves, stone adulterers and force women to wear stifling black burqas while other societies reject these practices; it is simply that some societies believe such things are right and moral while others deny this. It is not differing factual knowledge that causes Roman Catholics to reject the use of birth control and Protestants to allow it; it is a genuine clash of opinion over the morality of this practice. Similar statements could be adduced for most of the issues on the above list. Lewis’ argument is plainly and obviously wrong on this point.

But if there is no universal Law of Nature, no moral code common to all human societies, then Lewis’ argument for the existence of God collapses. Lewis’ case hinges on the assertion that not only is there an absolute morality, but that every human being is aware of it, and yet we have seen that this is not true. By contrast, an atheist can consistently believe both that morality is objective, but that not every human society has recognized this.

A few closing notes are in order for this section. In attempting to claim that no society has ever had a truly different morality, Lewis writes that people “have always agreed that you ought not to put yourself first. Selfishness has never been admired” (p.5). But capitalism, the economic system that almost all modern societies are built on, in a very real sense rewards and encourages selfishness. Executives who got to the top of the heap through backstabbing and self-serving behavior very often are admired in the business world. Lewis also writes that “Men have differed as to whether you should have one wife or four. But they have always agreed that you must not simply have any woman you liked” (p.5). Why he feels that the choice between monogamy and polygamy does not constitute a major moral difference is unclear, but even the point as he phrases it is wrong. The Bible itself provides an example of men choosing “any woman they like”:

“When thou goest forth to war against thine enemies, and the Lord thy God hath delivered them into thine hands, and thou hast taken them captive, and seest among the captives a beautiful woman, and hast a desire unto her, that thou wouldest have her to thy wife; then thou shalt bring her home to thine house, and she shall shave her head, and pare her nails; and she shall put the raiment of her captivity from off her, and shall remain in thine house, and bewail her father and her mother a full month: and after that thou shalt go in unto her, and be her husband, and she shall be thy wife.”
–Deuteronomy 21:10-13 (KJV)

In an amusing passage from the preface, Lewis even contradicts his own argument:

“Ever since I served as an infantryman in the first world war I have had a great dislike of people who, themselves in ease and safety, issue exhortations to men in the front line. As a result I have a reluctance to say much about temptations to which I myself am not exposed. No man, I suppose, is tempted to every sin. It so happens that the impulse which makes men gamble has been left out of my make-up; and, no doubt, I pay for this by lacking some good impulse of which it is the excess or perversion. I therefore did not feel myself qualified to give advice about permissible and impermissible gambling: if there is any permissible, for I do not claim to know even that. I have also said nothing about birth-control. I am not a woman nor even a married man, nor am I a priest. I did not think it my place to take a firm line about pains, dangers and expenses from which I am protected; having no pastoral office which obliged me to do so” (p.ix).

If Lewis asserts that all people have innate knowledge of a universal moral law, then how can he say he has no qualifications to give moral advice on topics he personally has never had to deal with? Surely he would be just as qualified as anyone else. Doesn’t the “Law of Nature” tell him whether those things are ethical or not?

Lewis closes the section with a hilariously bad analogy:

“We want to know whether the universe simply happens to be what it is for no reason or whether there is a power behind it that makes it what it is. Since that power, if it exists, would not be one of the observed facts but a reality which makes them, no mere observation of the facts can find it. There is only one case in which we can know whether there is anything more, namely our own case. And in that one case we find there is. Or put it the other way round. If there was a controlling power outside the universe, it could not show itself to us as one of the facts inside the universe – no more than the architect of a house could actually be a wall or staircase or fireplace in that house. The only way in which we could expect it to show itself would be inside ourselves as an influence or a command trying to get us to behave in a certain way. And that is just what we do find inside ourselves” (p.19).

The possibility of an architect entering a house that he designed to introduce himself to the people living there seems not to have occurred to Lewis. Again, he weakens his own argument by overreaching a point: just because he believes that God, if he exists, would disclose his existence to us through internal revelation, it does not follow that this is the only way God could possibly do this.


At the end of the previous section, Lewis concluded that he had not yet established the truth of Christianity. “Do not think I am going faster than I really am. I am not yet within a hundred miles of the God of Christian theology. All I have got to is a Something which is directing the universe, and which appears in me as a law urging me to do right and making me feel responsible and uncomfortable when I do wrong” (p.20). Surprisingly, he even admits that the evidence he has covered up to this point points to a deity unlike the one believed in by Christians: “We have two bits of evidence about the Somebody. One is the universe He has made. If we used that as our only clue, I think we should have to conclude that He was a great artist (for the universe is a very beautiful place), but also that He is quite merciless and no friend to man (for the universe is a very dangerous and terrifying place)” (p.23).

Having proved, or so he believes, the existence of God, Lewis goes on to examine rival conceptions of God. First, he briefly considers atheism and decides it will not do.

“My argument against God [when I was an atheist] was that the universe seemed so cruel and unjust. But how had I got this idea of just and unjust? A man does not call a line crooked unless he has some idea of a straight line. What was I comparing this universe with when I called it unjust?” (p.31)

If Lewis was indeed ever an atheist, he was obviously not one who thought too deeply on the subject. Human beings have the ability to imagine situations that do not in fact obtain and determine how they differ from the reality we do inhabit. The answer to his question is simple: We can compare this universe with one which we can conceive of where there would be perfect justice, and determine where ours is lacking by comparison. Similarly, a researcher attempting to cure a child with a hereditary disease need not be stymied just because they have no experience of what that child would be like without the disease; they can imagine what that situation would be like, and use that conception to guide and give meaning to their actions. Why might we desire to live in a world where there was justice? Simply stated, because all human beings desire to be happy, and because a world where justice was enforced would, in general, give rise to far more happiness for many more people than one where it was not.

Lewis next considers dualism, the view that there are opposing good and evil gods in the universe. While he gives this view credit for explaining the unsatisfactory nature of reality as we find it, he claims that it will not suffice. But the argument which he uses to defeat it, though he seems not to be aware of this, is not his own invention but something which has existed for a very long time.

“Now what do we mean when we call one of them the Good Power and the other the Bad Power? ….If ‘being good’ meant simply joining the side you happened to fancy, for no real reason, then good would not deserve to be called good. So we must mean that one of the two powers is actually wrong and the other actually right.
        But the moment you say that, you are putting into the universe a third thing in addition to the two Powers: some law or standard or rule of good which one of the powers conforms to and the other fails to conform to. But since the two powers are judged by this standard, then this standard, or the Being who made this standard, is farther back and higher up than either of them, and He will be the real God” (p.34).

Experienced readers will have recognized this argument: it is called the Euthyphro dilemma, and it dates back to Plato. But what Lewis fails to realize is that this argument is also equally applicable to Christianity. What does it mean to call God good? If it simply meant that his desires are in accord with what humans want, by Lewis’ own logic, God would not deserve to be called good. But, if this conclusion is rejected, there must be some external standard which is higher than God and by which God’s goodness can be judged.

Lewis then goes on to explain, if we reject dualism, how evil can exist in a universe where a supremely good and supremely powerful being reigns over all. Like most Christian apologists, he puts the blame on free will.

“God created things which had free will. That means creatures which can go either wrong or right. Some people think they can imagine a creature which was free but had no possibility of going wrong; I cannot. If a thing is free to be good it is also free to be bad” (p.37).

Again, Lewis fails to recognize two obvious counterexamples from his own theology. Does God have free will? If so, is there a possibility that he can misuse it to do evil? If not, why not? Secondly, what about Heaven? Lewis insists that free will is “the only thing that makes possible any love or goodness or joy worth having” (p.37), so we can assume it will exist in Heaven. If this is the case, what, if anything, will prevent people in Heaven from doing evil? (“Those Old Pearly Gates” discusses this example in more detail; see also “Divine Blackmail“.)

Finally, we reach the point where Lewis presents an argument for Christianity, out of all the world’s religions, being true. Incredibly, it is nothing but an embryonic form of the Lord/Liar/Lunatic trilemma debunked in “Unmoved Mover“. Lewis approaches the Bible with an attitude of naive trust, assuming that everything written in it is historically accurate, and concludes that since Jesus as it depicts him does not appear to be either a liar or an insane man, we have no choice but to believe his claim to be God was true. Skeptics are obviously not likely to be impressed by this. If we accept that the Bible is historically accurate, it would not much matter what we thought of Jesus’ personality – his miracles would leave us with little choice but to believe he was who and what the Bible says he claimed to be. But skeptics do not accept this, and Lewis provides no arguments to back up his claim of the Bible’s complete reliability.

Finally, he considers the question of why God, if he is all-powerful, does not simply put a stop to evil. Lewis certainly believes that he is capable of it, but wonders “whether people who ask God to interfere openly and directly in our world quite realise what it will be like when He does. When that happens, it is the end of the world. When the author walks on to the stage the play is over” (p.50).

But why should God’s intervention necessitate the apocalypse? According to the Bible, he has intervened in history before, often in very open and direct ways, without causing the end of the world. Readers will note that this is not the first time Lewis has attempted to prop up a weak point in his case with a metaphor rather than an argument; recall the “architect” analogy from the end of Book I.


Considering theism in general and Christianity in particular to be proved beyond all reasonable doubt, Lewis states that he will devote the remainder of the book to examining moral and theological issues from a Christian perspective. There are some sections worth praising here. One comes when he condemns the intrusive, sanctimonious brand of Christianity, unfortunately all too common today, that believes that society should ban anything that makes them uncomfortable or that they dislike. “One of the marks of a certain type of bad man is that he cannot give up a thing himself without wanting every one else to give it up. That is not the Christian way. An individual Christian may see fit to give up all sorts of things for special reasons – marriage, or meat, or beer, or the cinema; but the moment he starts saying the things are bad in themselves, or looking down his nose at other people who do use them, he has taken the wrong turning” (p.62).

In relation to this, Lewis also condemns the panicky, irrational position taken by far too many Christians that anything relating to sex is automatically wrong. “I do not think that a very strict or fussy standard of [sexual] propriety is any proof of chastity or any help to it, and I therefore regard the great relaxation and simplifying of the rule which has taken place in my own lifetime as a good thing” (p.74). Christians who fight against comprehensive sex education, doubtless on the grounds that trying to keep young adults ignorant of something will diminish their interest in it, would do well to take this advice.

Another commendable statement comes when Lewis points out that most Christians, far from taking moral advice from the Bible, are instead using it only to support their own pre-existing prejudice. “Most of us are not really approaching the subject in order to find out what Christianity says: we are approaching it in the hope of finding support from Christianity for the views of our own party” (p.67-68). He even states that the ideal Christian society would in many ways be leftist, a refreshing contrast to the American religious right who seem to firmly believe that Jesus supported preemptive war and tax cuts for the rich.

Finally, there is a statement that is frankly startling in its candor, and one I wish could be found in a great many more Christian apologetics works: “I am not asking anyone to accept Christianity if his best reasoning tells him that the weight of the evidence is against it. That is not the point at which Faith comes in” (p.108). This is a welcome relief from the monotonous chants of apologists who claim that all atheists are “without excuse” and that Christianity is true no matter what the evidence says; and in return, I will say that I would never counsel anyone to be an atheist if they did not sincerely believe that it was most likely to be the correct position.

However, these things being said, I must now turn to the parts of this section I cannot agree with. One comes when he writes, “we shall not be well so long as we love and admire anything more than we love and admire God” (p.98), and again, “I cannot learn to love my neighbour as myself till I learn to love God” (p.68). This is another example of how religion tries to take exclusive possession of a basic aspect of human life and claim that those who do not have its permission are not allowed to feel human. As an atheist, I take offense at the implication that I am somehow unwell or that I cannot truly love people just because I do not believe in God, and I am certain many nonbelievers who have friends, families and loved ones just like everyone else feel the same way.

There are also some repugnant comments that essentially nullify the earlier commendable statements about sexuality. For example, Lewis labels homosexuality the “perverted desire of a man for a man” (why do lesbians always get off so lightly?) and “quite unnatural” (p.70), calling it a psychological disease. He also proclaims that, as far as sex goes, the only two acceptable choices are completely faithful lifelong marriage to one person or else total abstinence, and goes so far as to call extramarital sex “a monstrosity” (p.81). This label is unacceptable. Murder, rape, bigotry, war, tyranny are monstrosities; two adults who love each other and want to express that love through an act of mutual pleasure and gratification, but who have not had a priest wave his hands over them and speak magic words, are not committing a monstrosity. Of course, sex is a powerful emotional experience, with a potential for causing harm equal to its potential for creating happiness, and should not be indulged in lightly or before both parties are fully ready; but again, this is not something religion owns, to be parceled out only as it sees fit.

There is one more statement in this section that deserves criticism. In his description of an ideal Christian society, Lewis states (though he seems somewhat embarrassed about it himself) that one aspect of such a society would be that wives would be required to obey their husbands. The justifications he gives for this are based on outlandish and insulting prejudices:

“If there must be a head, why the man? Well, firstly, is there any very serious wish that it should be the woman? As I have said, I am not married myself, but as far as I can see, even a woman who wants to be the head of her own house does not usually admire the same state of things when she finds it going on next door. She is much more likely to say ‘Poor Mr. X! Why he allows that appalling woman to boss him about the way she does is more than I can imagine.’ I do not think she is even very flattered if anyone mentions the fact of her own ‘headship.’ There must be something unnatural about the rule of wives over husbands, because the wives themselves are half ashamed of it and despise the husbands whom they rule….
        The relations of the family to the outer world – what might be called its foreign policy – must depend, in the last resort, upon the man, because he always ought to be, and usually is, much more just to the outsiders. A woman is primarily fighting for her own children and husband against the rest of the world…. The function of the husband is to see that this natural preference of hers is not given its head. He has the last word in order to protect other people from the intense family patriotism of the wife” (p.88-89).

What exacerbates this ridiculous stereotyped view is Lewis’ stated opposition to divorce no matter the circumstances, even if both partners no longer love each other, even if one of them falls in love with someone else (although, to his credit, he does say that this is a rule for Christians and should not be imposed on the populace in general). Based on this, and based on his explicit statement that the last word in any marital disagreement should ultimately be the husband’s, one can only conclude that Lewis believes that a woman married to a man who is abusive or insensitive to her emotional needs should simply stay in that unhappy marriage for the rest of her life.


The final section of Mere Christianity discusses specific Christian theological issues such as the nature of the Trinity. There is little here relevant to this review, but there is one remark near the end that I find praiseworthy, and one I hope more Christians will take to heart:

“But when we are comparing Christians in general with non-Christians in general, we are usually not thinking about real people whom we know at all, but only about two vague ideas which we have got from novels and newspapers. If you want to compare the bad Christian and the good Atheist, you must think about two real specimens whom you have actually met. Unless we come down to brass tacks in that way, we shall only be wasting time” (p.162-163).

I could not agree with this sentiment more. I correspond with many Christian visitors to my website, and while some of them are reasonable, friendly people who are willing to accept my own definition of my position, many seem to have gotten their views on what atheism is and what an atheist believes straight from the worst false stereotypes of apologetic literature. I suspect few of these people would think an atheist truly understood Christianity if all his knowledge of it was derived from atheist books and literature, so how can they feel qualified to discuss atheism knowledgeably when the reverse situation holds? The only reliable way to learn what any worldview is really all about is to ask someone who actually holds it.


C.S. Lewis is plainly a gifted writer. Mere Christianity was a quick and enjoyable read, with an engaging and conversational tone, doubtless recapturing some of the atmosphere that accompanied it when it was first broadcast as a series of radio talks. Its reasoning was easy to follow, and the text was peppered with analogies, many of which are quite clever.

However, while this was a literary strength, logically it was a key weakness. There are places where Lewis’ argument is weak or patently flawed, but rather than trying to shore it up by presenting additional facts, he simply restates it as a metaphor. This does not make his case any stronger. He also fails to address several crucial and obvious counterarguments to his points, and has an unfortunate tendency to attempt to downplay or conceal exceptions that refute his arguments, rather than confronting them honestly and openly. The section in the preface where he recommends concealing from prospective converts information that might change their mind about Christianity is the most glaring example; his casual and incurious dismissal of the stark moral differences between cultures, even though his argument absolutely depends on there being no such differences, is another. This is why I summarized this book as “cotton candy apologetics”: fluffy and easy to consume, but ultimately insubstantial.

I do not mean to suggest that Lewis himself was unintelligent. The sections on Christian morality and theology do show evidence of rational consideration and careful reflection; the problem, as it seems to me, is that although he has clearly put a lot of thought into what it would mean for Christianity to be true, he has not invested comparable intellectual effort into arguing that Christianity is indeed true. Instead, he largely takes this for granted. Even when he explicitly argues in favor of it, his arguments have a hurried, cursory feel, as if he were trying to get this boring business out of the way in order to get to the topics he really wanted to talk about. While Christians may find Mere Christianity informative and may even be stimulated to think about their faith in a different way, I sincerely doubt that such shallow argumentation will ever convert a knowledgeable nonbeliever.