“Mere Christianity” by C. S. Lewis—A Book Review

Mere Christianity is Lewis’ attempt to explain and defend the common beliefs among Christians (across denominations) to non-Christians. Thus, mere Christianity refers to the basics that all who profess to be Christians agree. Lewis has four topics in this book, which were originally talks given on the radio. In Book 1, Lewis argues for right and wrong as a clue to the meaning of the universe. Book 2 talks about what Christians believe, and Book 3 addresses Christian behavior. Finally, Book 4 is about what Lewis calls “first steps in the doctrine of the Trinity.”


In Book 1, Lewis, speaking to a non-Christian audience, argues that man’s sense of right and wrong (Law of Nature) points to the reality of God. Anyone who argues that a standard of right and wrong does not exist will complain that “it is not fair” when a promise to him is broken. Lewis points out that while all human beings acknowledge that an unavoidable standard of proper behavior exists, but they break it. To those who object the existence of a moral law, he argues that the very fact that difference exists between ideas of what is “proper behavior” only proves that such a standard exists—or else there is no point for arguing the differences. Behind the moral law is key in understanding the universe. Where does the sense of right or wrong come from? The two most common views are the materialistic view (evolution), religious view, and a combination of the two (e.g., theistic evolution). Lewis argues that to prove one or the other is beyond the capacity and role of science. Behind the moral law is someone beyond this material universe. The universe and the moral law in man’s minds point to a designer who is interested in right conduct—a “good God”. But God is good, not in the sense that he is indulgent, soft, or sympathetic; rather, he is God in the sense of absolute goodness who disapproves human greed, trickery, and exploitation with no exception. If an absolute goodness exists, then it must hate most of what human beings do. By acknowledging this can the Christian’s message only make sense—the message of repentance and the promise of forgiveness. It is the explanation of how the demands of God’s moral law, which no one can meet, have been met on man’s behalf through God becoming man to save mankind from God’s disapproval.

Book 2 focuses on what Christians believe, with an evangelistic emphasis on the Gospel. Lewis points out that the majority of the world believe in some kind of deity. Unlike Pantheism, Christianity distinguishes the Creator from his creation just like a painter is not a picture. Responding to the atheistic argument against the existence of God because of the existence of injustice, Lewis asks where did the idea of just and unjust come from? If the world is unjust, then there must be a sense of justice, or else one would not be able to say “unjust” unless there is an idea of what is “just.” On the other hand, the water-down Christianity where God is good and everything is all right leaves out the difficult realities of suffering, sin, hell, and redemption. Against dualism, Lewis argues that there cannot be two equal powers, which is good and evil for who decides what is evil and what is good? Lewis argues that,

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. In fact, what we meant by calling them good and bad turns out to be that one of them is in a right relation to the real ultimate God and the other in a wrong relation to Him…. Christianity agrees with Dualism that this universe is at war. But it does not think this is a war between independent powers. It thinks it is a civil war, a rebellion, and that we are living in a part of the universe occupied by the rebel.

pp. 43, 45

There must be some law or standard beyond the two powers that judges them. Once a standard is placed, then it is evident that good relates to God, and wickedness is a perversion of God’s goodness. Good must exist before there can be evil. Wickedness is nothing but a pursuit of something good in the wrong way. Sin is always done because it is either pleasing or useful to the one who sinned. Then comes a Jew who said that he has always existed, talked as if he was God, and claimed to forgive sins. Jesus forgiving people’s sins only makes sense if he was the God whose laws were broken. Thus, it is foolish to accept Jesus as a great moral teacher, but not accept him as God. He is either a lunatic, a man who claims to be God, or he is truly God made flesh as he claimed to be. For Lewis, the central belief of Christianity is that through Christ’s death man can be made right with God. Unlike other religions, Christians do not believe that that trying to be good so God will love us; rather, God will make us good because He loves us (p. 63).

Book 3 is about Christian behavior. Lewis argues that morality is what keeps humanity from falling apart like rules for using machines properly to prevent a breakdown (p. 69). Morality prevents human breakdown by being concerned with the harmony between individuals, harmony inside each individual, and finding the purpose of life given by his Creator (p. 72), which differentiates Christian morality from non-Christian. Regarding social morality, Lewis argues that a Christian society will not arrive unless it is desires, but one cannot learn to love his neighbor unless he learns to love God by obeying him first (p. 87). Regarding morality and psychoanalysis, Lewis distinguishes the two: psychoanalysis is concerned about the feelings and impulses behind a moral choice, but morality is concerned about the acts of choice themselves (pp. 89-91). Morality is about the free choice of man—will he put his own advantage first or will he put it last? Most of the chapters focus on what Lewis’ lists of Christian virtues. The four cardinal virtues are prudence, temperance, justice and fortitude. Chastity, which Lewis calls “the most unpopular of the Christian virtue,” limits sexual intimacy within marriage. Put positively, Christian marriage is the idea from God for a man and wife to be “one flesh” for life. Forgiveness is extended to enemies even in the context of war, and war, though dreadful is sometimes necessary. What Lewis calls the great is pride, on what he calls “the complete anti-God state of mind” surpassing the vices of unchastity, anger, greed, and drunkenness. He ends this section with discussion on three “theological” virtues: charity, hope, and faith.

Book 4 is Lewis’ theological treaties. He likens theology to a map towards better understanding Christianity. He begins by affirming that Jesus Christ is the Son of God. He describes the Trinity this way: “In God’s dimension…you find a being who is three Persons while remaining one Being, just as a cube is six squares while remaining one cube” (p. 162). Lewis, however, acknowledges the difficulty of understanding the concept of the Trinity. He redirects the conversation to being drawn into God. People have a sense that deity exists, then Jesus came and claimed to be God, but he was also man. Those who believed in him formed into a community led by God inside them [Holy Spirit]. They finally came to realize the doctrine of the Trinity. Lewis then talks about God’s relationship with time—being outside time (for he created time), yet enters in time. Back to the Trinity, Lewis argues that the statement “God is love” have no meaning unless God is at least two Persons. Thus, the love within the Godhead has been eternal. What God did for man is to send the Second Person of the Godhead to become human, died, and rose again. Lewis challenges his readers to appropriate this salvation (p. 181). The Son is transforming and turning us into little Christ. But followers of Christ must count the cost, yet Christ is not only after one’s improvement, but one’s transformation. He is making his followers new men.


Mere Christianity is a classic literature for a reason. C. S. Lewis exhibits his skill as a writer by simplifying difficult theological and philosophical ideas into understandable and concise bites. Lewis provides several illustrations and analogies that simplify profound truths. He has demonstrated that, contrary to secular thinking, Christianity is not against rationale and logic. While human thinking is limited and not the final basis of faith, Christianity is not against it. Believing the claims of Christianity, though through faith, is not based on blind faith.

One of the benefits of Mere Christianity is that it challenges the secular mind not to dismiss Christianity too soon, but to probe deep into the foundation of the beliefs of Christianity. Lewis’ classic work is a helpful guide to read with a non-Christian who struggles in understanding Christianity. Lewis’ argument on the existence of God based on the universal concept of morality is helpful. The universal complaint, “it is not fair,” points to an existence of a moral standard that transcends culture and generation. Ultimately, it points to a good God who set up these standards in his universe. Lewis is dealing with ultimate reality concepts, such as the existence of God and God’s creation of man. These realities lead to serious implications about man’s responsibility before God and proper function on God’s universe. With great skill, Lewis redirects these ideas into the heart of the gospel message—the demands of God’s moral law cannot be met, but God calls man to repentance with his offer of forgiveness (pp. 30-32). The dilemma of man’s accountability before God and the impossibility of the meeting the standards of morality can only find its solution from the claims of Christianity. Lewis is also helpful in confronting, not only the secularist, but also the religious man. Regarding the claims of Jesus, Lewis argues that it is foolishness to accept Jesus as a great moral teacher, while denying his deity. Jesus is either God or a lunatic (p. 52). This confronts both the religious people of Lewis’ day and today.

The section on Christian morality touches on helpful discussion in understanding Christianity and its role in society. Particularly helpful is Lewis’ personal experience as he discusses certain aspects of Christian morality. Being a war veteran, Lewis’ treatment on the topic of forgiveness and forgiving the enemy is convicting and heartfelt (pp. 115-120). Being a non-married man during the time of this writing, his convictions on chastity were constructive. He encourages those who have failed to ask forgiveness, try again, and depend on God (p. 101). Even more useful is his caution about making sexual ethics the center of Christian morality. He argues that

A cold, self-righteous prig who goes regularly to church may be far nearer to hell than a prostitute. Of course, it is better to be neither.

p. 103

A few things, however, I find to be disappointing. Certainly, Lewis’ goal as stated at the beginning is to provide a treatise on the most basic ideas of Christianity that everyone will agree on, regardless of one’s denomination. Yet it is disappointing to find Roman Catholics to be included here (p. xi). In the first chapter of Book 2, Lewis argues that other religions are not simply wrong all through—they have some hint of the truth. This is certainly true, but such language need caution when adopted into today’s post-modern and pluralistic culture (perhaps not so much during Lewis’ context). For sure even the non-religious at times have some hint of truth, but is partly true considered truth? Doesn’t the definition of truth require “truth” to be an absolute truth? To be fair, Lewis later says that there is only one right answer, but some of the wrong answers are nearer than others (p. 35).

Lewis’ arguments are helpful, but only to a certain extent. Some logical arguments, when taken to its ultimate logical conclusion falls short on representing the biblical truth. Regarding God and time, Lewis speculates,

In a sense, [God] does not know your action till you have done it: but then the moment at which you have done it is already ‘Now’ for Him.

P. 170

This statement is motivated by Lewis’ view on free will and how that interacts with God’s omniscience and eternality. He though later admits that such view can be left alone since “it is not in the Bible or any of the creeds” (p. 171).

Another area where Lewis’ free will creates problems is in the area of sanctification and perseverance. He argues that God can make us creatures that can obey his commands if we let him—but we can also prevent him, if we choose (p. 205). In this context, he seems to be speaking to those who have already turned to Christ (p. 204). This leads to one of Lewis’ problematic ideas. He suggests that there are those who “belong to Christ without knowing it” (p. 209). He illustrates that

A Buddhist of good will may be led to concentrate more and more on Buddhist teaching about mercy and to leave in the background (though he might still say he believed) the Buddhist teaching on certain other points.

p. 209

This undermines Lewis’ earlier argument on the necessity of viewing Christ as the Son of God, or reject him as a lunatic. While the gospel message is contained throughout Lewis’ work, it is not as clearly presented in such a way that a non-Christian would clearly get what it is.


It seems that the areas I find Lewis disappointing is in the discussions where philosophy takes over clear biblical teaching. Since Lewis’ approach is based on logic and rationality, its expression of the realities of God and Christianity will naturally be limited. In the end, the best way to understand the basics of Christianity—the mere Christianity—remains to be through God’s special revelation, the Bible. Any other means will naturally fall short. Yet, perhaps, Lewis was attempting to reach out to those who do not presuppose that the Bible is God’s Word, or maybe his confession at the onset that he is no theologian but only a layman inhibits him from appealing to biblical interpretation to support his arguments.

Despite these weaknesses, however, Mere Christianity remains to be a classic work that every Christian and non-Christian should read. Its writing style is engaging, and its arguments are compelling. There is no writer like C. S. Lewis that writes with sharp, logical, creative, challenging, and concise arguments. Lewis thinks clearly and writes clearly. Non-Christians should give Lewis a hearing when probing into Christianity. Christians should value Lewis’ analogies and useful arguments on critical issues concerning apologetics, philosophy, and morality.

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