PDF Summary:Mere Christianity, by C. S. Lewis

In Mere Christianity, C.S. Lewis sets out to explain and defend Christian beliefs to a skeptical modern audience through a series of essays—originally delivered as a series of radio addresses in the United Kingdom between 1941 and 1944. Through these essays, Lewis—whom many Christians regard as an important lay theologian—argues for the existence of God, the divinity of Christ, and the benefits of a virtuous life.

In this guide, you'll learn about the objective nature of morality, the personal surrender required to align your life with Christian virtue, and whether Christians hold God responsible for creating evil. Our guide will also explore the philosophical traditions behind Lewis's arguments while comparing his ideas to other variations of Christian doctrine.

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(Shortform note: While most people today agree that only agents capable of making moral decisions can be considered moral or immoral, ancient cultures harbored some very different ideas about the nature of good and evil. Early religions often attributed all types of natural evil—including both bad decisions and bad events like droughts, plagues, or famines—to sources of absolute cosmic evil, like powerful demons or evil gods. While modern ethicists may dismiss the idea of a cosmic and absolute evil, this concept still frequently reappears in popular entertainment franchises like “Star Wars” or “The Lord of the Rings.”)

Other Solutions to the Paradox of Evil

Lewis's arguments on free will belong to the tradition of theodicy (literally "defense of God"), a practice of explaining how evil can exist in a world created by a God who is infinitely good. However, Christian thinkers have proposed a wide range of solutions to this question. Here, we'll review a few of the major alternatives.

Evil is a test from God. In the book of Job, God inflicts suffering on Job to test his commitment. Here, the question is not whether God's actions are right, but whether Job can remain committed to God in spite of his suffering. In this view, God has the right to test humans' faith.

Evil exists for our moral development. The Greek theologians Irenaeus and Origen argued that Earth is like a hospital or a school for the soul. Evil exists so that we can learn from it as we become greater moral beings ourselves.

Evil is simply the absence of good. St. Augustine argued that good is a positive quality created by God and that evil is simply the absence of good—much in the way that physicists consider coldness the absence of heat rather than a positive property of “coldness.”

Part 3: Christian Virtues

God calls on everyone to choose good over evil, but how do we know what is “good”? Lewis argues that Christianity instructs us to be good by following Christian virtues, or moral principles that can be applied to a wide range of situations. This section will provide a brief overview of what those virtues are, as well as some of the benefits of choosing a virtuous life.

The Four Key Christian Virtues

Lewis explains that following God's moral law requires living your life according to four key Christian virtues: faith, benevolence, moderation, and humility.

Virtue #1: Faith

Lewis defines faith as a commitment to and trust in Christian teachings in the face of daily distractions and doubts. Lewis pushes back against the widely held idea that faith entails a blind or thoughtless belief in Christian doctrine. In fact, he writes that you should not believe in Christianity if you don’t think the evidence supports it.

Lewis also asserts that faith requires you to greet life with hope and optimism. To accept Christianity is to believe that there is something better in the next life and that the power of good is greater than the power of evil, both of which give you a reason for a hopeful outlook.

Does Faith Require Evidence?

Lewis argues that faith is not the same thing as blind acceptance. However, many of Christianity's most strident critics argue that faith and blind acceptance are one and the same. For example, Richard Dawkins, writing in The God Delusion, argues that belief without evidence is the "essence" of faith.

There are two contrasting schools of Christian thought on whether faith requires evidence: fideism and evidentialism.

Fideism advocates faith without evidence. It is the belief that faith is opposed to reason, but of the two, faith is superior. Scholars associate this perspective with the 17th-century French philosopher Blaise Pascale. He argued that religion is mysterious and unknowable by nature, and therefore it is senseless to expect rational proofs for religion.

Evidentialism is the belief that religious doctrines must be supported by evidence. Evidentialist Christians argue for the existence of God and the veracity of Christian doctrine with logical proofs that don't rely on presupposed Christian faith. By stating that you shouldn't believe in Christianity if you don't accept the evidence, Lewis aligns himself with evidentialism.

Virtue #2: Benevolence

Benevolence is the virtue of treating others with kindness, fairness, and forgiveness. Essentially, benevolence requires you to unconditionally and universally treat all others with the same consideration that you would like them to show you. This includes loving and forgiving your enemies.

This raises a challenging proposition: how do you love those who have harmed you? Lewis argues that you don’t have to like what someone did to still love them as a person. You can love the person while hating their actions. While it may sound difficult to keep these two things separate, Lewis argues that we all have practice making this distinction: This is how we treat ourselves. Most people dislike their own vices, evil deeds, and faults while still managing to love themselves as people. Thus, the virtue of benevolence simply requires giving the same nuanced consideration to everyone else that we give to ourselves.

What Does Psychology Have to Say About Forgiveness?

In addition to the spiritual requirement for forgiveness asserted by lay theologians like Lewis, psychologists argue that forgiveness provides many important benefits for our well-being. For the person who forgives, forgiveness can provide the release of unhealthy anger and resentment, a chance to heal from past wounds, and a chance to move on with their lives. For the person being forgiven, forgiveness can lead someone to acknowledge harm they have caused and seek moral growth. Forgiveness also benefits both parties by creating an opportunity to restore the relationship.

However, most psychologists reject the idea that forgiveness is an obligation or a duty, as Lewis suggests. They argue that pressuring someone to forgive who is unready or unable can be detrimental to their well-being, especially if it requires opening up unprocessed trauma.

While Lewis argues that we do have a duty to forgive our enemies, he acknowledges that only those who have cultivated their virtue may be able to forgive serious wrongs. For example, addressing a British radio audience during World War II, Lewis told his listeners that if they can't forgive the Nazis, they can start by forgiving their neighbors and work their way up.

Virtue #3: Moderation

Lewis explains that moderation is the ability to control your appetites and impulses. Christian virtue calls on you to practice self-control when it comes to food, alcohol, sex, and other forms of indulgence and sensual pleasure. He explains that moderation sometimes calls on you to limit how much you consume, but it can also require you to recognize the things you need to give up entirely if they are too difficult for you to control.

(Shortform note: While Lewis approaches moderation from a religious perspective, many psychologists consider moderation to be just as important to general psychological well-being. In Dopamine Nation, Anna Lembke writes that compulsively indulging in pleasurable activities like drugs, sex, or gambling can cause your brain to develop a "tolerance" to pleasure. This will force you to seek these pleasurable activities in increasingly high amounts just to keep from feeling bad, thereby locking you into a cycle of addiction.)

Lewis writes that sexual appetites require more specific instructions than other bodily appetites. He provides two reasons why.

1. The difference in intensity: Lewis argues that the appetite for sex is out of proportion with its purpose. While sexuality is essential for creating children, Lewis writes that sexual appetites arise more often than is necessary for pursuing this end.
2. The difference in consequences: The consequences of indulging in compulsive sexuality are higher than those of compulsively overeating or drinking alcohol. Lewis writes that overindulgence in sex can lead to the creation of unplanned children that partners may not be willing or able to support.

Because sexual appetites are different from other temptations in both their intensity and consequences, Lewis argues that they require a different solution than moderation. In traditional Christian teaching, the solution is a strict binary choice: abstinence or monogamous marriage. This will, at minimum, prevent the birth of children who lack two committed parents to support them. Thus, Lewis argues that the only acceptable place for sexuality is within a monogamous marriage. He also argues that the Christian conception of marriage is not primarily focused on feelings or personal fulfillment, but rather on having children and creating a stable home in which to raise them.

What Do Other Major Religions Say About Premarital Sex?

Lewis argues that the Christian prohibition on sex outside of marriage is not simply a preference of the Christian religion, but a response to fixed features of human nature. Recall also that Lewis argues that morality differs very little between cultures on the important issues. By this logic, we’d expect the world's other major religions to share Christianity's view on premarital sex—but is this the case?

To answer this question, let’s explore what the world's three next largest religions (by number of adherents) say on this point.

Islam: Like Christianity, Islamic doctrine strictly prohibits premarital sex and adultery. A study measuring the frequency of premarital sex by religion shows that Muslims are less likely to report engaging in premarital sex than followers of any other major religion.

Hinduism: Hindu teachings on sexuality vary from region to region—unlike Christians or Muslims, Hindus don't universally adhere to the same set of holy texts. In general, Hindu teachings determine the morality of a sexual act based on its intention and consider procreation within marriage a much better intention than personal pleasure. While Hinduism typically does not strictly prohibit premarital sex, Hindu societies have very strong social taboos against premarital sex that aren’t considered part of the religion. According to the above-cited study on the frequency of premarital sex, Hindus are less likely to report engaging in premarital sex than Christians, but more so than Muslims.

Buddhism: Buddhism also does not explicitly prohibit premarital sex. However, Buddhists consider any craving for pleasure to be a source of suffering, and therefore monks and nuns adhere to strict celibacy. Buddhist morality judges all actions by their consequences, so reckless sexual behavior could be considered immoral if it leads to a negative outcome. That said, Buddhists are more likely to report having premarital sex than Christians, Hindus, or Muslims.

Virtue #4: Humility

Out of all the Christian virtues, Lewis considers humility to be the most important. Humility is the recognition of a modest position in the world, especially when faced with the infinite superiority of God. Humility is the opposite of arrogance and pride, and the opposite of satisfaction in one's own achievements, importance, or capacities. Lewis considers pride the worst sin of all. He offers two reasons why pride is so destructive.

1. Pride turns you away from other people. Lewis argues that when you seek to put yourself above others, their achievements contradict your high opinion of yourself, resulting in jealousy, resentment, and a loss of self-esteem. This makes it harder to be benevolent toward others. Therefore, pride becomes an obstacle to the Christian commitment to treat others with charity and love. Pride will leave you isolated and destroy the natural bonds of community, friendship, and family.

2. Pride turns you away from God. Recall that being virtuous requires submitting yourself to the moral law of a superior being. The more arrogant you are in your own sense of right and wrong, the less capable you are of submitting to that higher power. Therefore pride turns you away from your relationship with God, and consequently away from the source of your virtue. Lewis argues that pride is the worst sin because it has the power to undermine all your virtues.

What Is the Difference Between Pride and Self-Esteem?

Most psychologists recognize that it's important to have a healthy love and respect for yourself, which is sometimes called “pride.” However, they also recognize destructive forms of high self-regard, which they often refer to as arrogance, narcissism, or vanity. This raises a difficult question: How are we supposed to tell the difference between arrogance and self-esteem? Psychologists offer four key distinctions.

1. Difference in purpose. Some psychologists argue that the distinction between pride and self-esteem lies in motivation. When you hold an inflated sense of self to cover up low self-esteem or make yourself feel superior to others, this is arrogance as opposed to self-esteem, and it pushes you away from other people. The desire for superiority is the part of pride that Lewis considers most toxic to your virtue, as surrendering to God requires recognition of your inferiority when faced with the divine.

2. Difference in proportion. Some explanations distinguish between self-esteem and arrogance by measuring quantity: Self-regard is good in small amounts, but becomes a problem once you acquire an immoderate or excessive amount of it.

3. Difference in source. Some maintain that the difference between arrogance and self-esteem lies not in how highly you esteem yourself, but in how you understand the underlying source of your positive qualities. Healthy self-esteem comes from recognizing effort, whereas unhealthy arrogance comes from belief in consistent, internal qualities. For example, saying you won a race because you practiced is self-esteem, but claiming to have won because you're just amazing is arrogance.

4. Difference in consequences. Psychologists also differentiate healthy self-esteem, which is linked to empathy and positive reactions toward others, from arrogance, which is linked to lower empathy and increased hostility toward others. This confirms Lewis's argument that pride drives you away from others and undermines your virtues.

The Three Purposes of Christian Virtue

Lewis explains that virtue is essential to human thriving. He pushes back on critics of Christian morality who maintain that a life of Christian virtue simply prevents people from enjoying themselves and indulging bodily appetites for sex, food, or alcohol. Instead, Lewis asserts that pursuing virtue, though challenging, will ultimately help people live happier and more fulfilling lives. He argues for three distinct purposes.

Purpose #1: Social morality is how people treat each other and is what most people think of first when they consider ethics. Social morality includes treating each other kindly and fairly. It improves our quality of life because if everyone behaved ethically toward each other, the world would be a better place.

(Shortform note: Many modern theories of ethics focus almost exclusively on this first purpose. In particular, contract theory holds that morality is a set of agreements that allow people to live together. In The Righteous Mind, Jonathan Haidt argues that moral systems make all societies possible because they induce people to put the interests of the group above their own personal interests.)

Purpose #2: Cultivating character—the practice of developing habits of virtue—largely benefits your inner life. Lewis argues that as you align your life with your values, you will experience greater levels of inner harmony and lower levels of personal distress. Living in alignment with your values frees you from the need to rationalize actions that violate your own moral code.

Purpose #3: Finding purpose allows you to experience a greater sense of meaning in your life. Lewis argues that for a truly virtuous life, it is not enough to simply be nice to others and practice cultivating character. You must also think about the greater aim of your life, and set your sights on virtuous goals.

Does Psychology Confirm Christian Virtue?

Many psychologists’ ideas regarding general well-being align with Lewis’s ideas on the benefits of virtue and his claim that living virtuously can ultimately help you live a better life.

Researchers have confirmed the importance of living in alignment with your values and beliefs. Living out of alignment can result in cognitive dissonance, or the mental toll of maintaining two contradictory values or beliefs at the same time. Cognitive dissonance often causes stress, anxiety, embarrassment, and a sense of guilt, as well as the need to constantly rationalize new information.

Like Lewis, psychologists emphasize the importance of a sense of meaning to your personal well-being. Victor Frankl (Man’s Search For Meaning), argues that human beings are naturally motivated by meaning more than pleasure or personal happiness. He asserts that people naturally want to understand the purpose they have contributed to their lives, and that this sense of contribution is the cornerstone of psychological health.

Part 4: Answering God's Call to Virtue

Lewis argues that the creator calls on each of us to be virtuous. In this section, we'll explore Lewis's explanation of how you can answer this call. We’ll discuss Lewis’s conception of God's high moral standards and how you must surrender your will to pursue them. We’ll also cover Lewis’s beliefs about how this effort will change you and why your intentions matter.

God Holds You to a High Moral Standard

Lewis writes that if moral laws are created by the highest power in the universe, this puts humanity in a terrifying position. Since moral laws are often broken, we have reason to believe that the highest power in the universe dislikes our actions. Lewis argues that you ought to be worried—even afraid. However, this worry should inspire you not to hide from God and moral laws, but rather to try to align your conduct with these moral laws. Your best response to this fear lies in finding the courage to commit yourself to a more virtuous life.

Lewis considers this no easy task. If God's moral laws are truly objective then they permit little leniency and few exceptions. Since you have no control over what is right and wrong, you can't decide to exempt yourself from certain rules, nor can you decide when your circumstances merit an exception or when the rules’ standards apply. Therefore, the work of being virtuous is never done.

(Shortform note: Research supports the idea that a person’s perception of God's moral standards can influence their behavior. One study found that people who believe in a wrathful, punishing God are less likely to cheat on an academic test than those who believe in a kind, forgiving God. This supports Lewis's contention that a God with high, rigid moral standards may serve as a greater spur to moral action than one with lenient moral standards.)

God’s Call to Virtue Requires Surrender

Lewis argues that becoming a moral person requires surrendering your will to God. Because you did not create the moral laws, your impulses, goals, and desires may not be aligned with them. Therefore, in moments where your will is in conflict with moral law, you must give in. When you give in to a will that conflicts with your own, you are surrendering and placing your trust in a higher power.

(Shortform note: Many Christian thinkers agree with Lewis that following God’s laws requires surrender. Rick Warren (The Purpose Driven Life) takes this a step further, arguing that God not only has a set of moral laws—he also has a plan for each human’s life. Warren contends that God created you and all your attributes for achieving a unique purpose in this world. Therefore, surrendering to God's will not only changes you into a more virtuous person, but it also sends you down the road to achieving your life’s ultimate purpose.)

Surrender Results in Transformation

Because you are surrendering your will, becoming virtuous will inevitably require you to become a different person than who you would have become without God. Lewis provides three reasons why.

1. As you strive to become virtuous, you will become more aware of morality. The effort to make moral choices will force you to spend more time thinking about right and wrong, thereby developing your capacity for moral thought. This will lead to becoming more aware of new opportunities to make moral choices.

2. Becoming more aware of right and wrong strengthens your moral conscience, leading it to hold you to a higher standard of conduct. Therefore your conscience will begin making more demands of you.

3. Once your conscience demands more from you, you will confront all your vices, not just some of them. Your moral awareness will naturally spread into new areas of your life where you hadn't previously considered the morality of your choices.

Cultivating Virtue as a “Feedback Loop”

Systems analysts would describe Lewis's process of moral development as a feedback loop. In Thinking In Systems, Donella H. Meadows describes two types of feedback loops, stabilizing feedback loops, and self-reinforcing ones.

A stabilizing feedback loop regulates itself to stay within certain boundaries, like a thermostat that cools a house when it's too warm and warms a house when it's too cool.

A reinforcing feedback loop moves in one direction, and can just keep spiraling bigger and bigger. For example, population growth is a reinforcing feedback loop: the more people reproduce, the more people will be able to reproduce in the next generation.

We can understand Lewis's description of virtue as a reinforcing feedback loop. As you practice virtue, you will become more aware of opportunities to continue practicing virtue, allowing you to spiral upward. This means that even a small step towards virtue can have enormous effects on your character in the long run, by setting you on a virtuous path.

God Is Concerned With Your Soul

If virtue comes from God and practicing virtue changes you into a new person, then it follows that God is not just concerned with how you behave but what kind of person you are. It matters to God who you are on the inside. Lewis argues there are three points we should take from this.

1. Motives matter. It is not enough simply to act in the right way, one must do so for the right reasons. To be virtuous, you must pursue virtue for its own sake. For example, if you give to charity for recognition, or help a neighbor to put them in your debt, you have not been virtuous.

2. Every choice matters. God is concerned with every decision you make, large or small, because choices accumulate over time, ultimately shaping the person you become.

3. Effort matters. Lewis writes that God understands the obstacles each of us faces in trying to become virtuous. While God's ultimate standards may be difficult to reach, he welcomes every attempt as a positive step. This does not mean God has different standards for everyone. Rather God expects effort at virtue from everyone no matter their stage of moral development.

Why Does God Care About Us?

A central tenet of Christian faith is that God cares deeply about us: God cares about each decision we make, our reasons for making it, and how much work we put into trying to be good. This raises a fraught theological question: Why? If God is truly all-powerful, then why does God care at all whether mere humans are living virtuously? Here we’ll explore three explanations.

• God cares about us because we have a role to play in completing creation. According to this view, God created us with the intention that we would live virtuous lives and join with him in the next life. Therefore, God expects us to be good so that it will complete his plan for creation. If God's plan is for us to be virtuous, then it matters why we make each decision.

• God cares about what we do because God loved us enough to create us and plan out our lives. It follows that God would care whether we make decisions that bring us closer to him and the lives he wants us to lead.

• God cares about our efforts to live more virtuously because human obstacles and mistakes are inevitable parts of life—it’s in making efforts to overcome and grow from these mistakes that God can see our true character and devotion to him.

Part 5: The Example of Christ

Lewis argues that Christian faith requires not simply surrendering to God's moral laws, but following a perfect example. Lewis writes that only Christ is capable of setting this perfect example of surrender because he is both human and divine. In this section, we'll explore Lewis’s arguments for Christ’s divinity, why Christ’s dual nature allows him to set the example of perfect surrender, and how Christian practice helps us to become more Christlike.

Christ’s Divinity

Before discussing how Christ's dual nature leads to a perfect example, Lewis lays a foundational argument for the divinity of Christ to help skeptics accept Christ's dual nature. He argues for Christ’s divinity with the following line of reasoning: Christ did not claim simply to be a moral teacher. He claimed to be the son of God, and that he had the power to forgive others' sins. Lewis asserts that Christ’s claim to divinity forces you to accept one of three conclusions:

• Conclusion #1: Christ was lying.
• Conclusion #2: Christ was completely insane.
• Conclusion #3: Christ was God as he claims to be.

Lewis argues that it is unlikely that Christ was either lying or insane. He cites the depth of wisdom and kindness in his moral teachings. He also notes that others who wrote about him spoke very highly of his character, praising his love and serenity. If Christ is neither lying nor insane, then he must be God. Lewis accepts Christ's divinity as the least implausible of the three choices and encourages readers to accept it as well.

Did Christ Claim Divinity?

Lewis's argument for Christ's divinity has become popular in public debates over Christianity—even taking on the name "Lewis's trilemma." However, the argument remains controversial even among Christians and biblical scholars. Most of the controversy centers on the first premise—Christ’s claim to divinity—with scholars disagreeing over how sure we can be that Christ actually made this claim. Here we'll review some of the common arguments for each side.

The New Testament Scholar Bart D. Erhman casts doubt on whether Christ claimed divinity as Lewis says. He points out that Christ claims divinity in the Gospel of John, but not in the synoptic Gospels (those of Mathew, Mark, and Luke). Since the synoptic Gospels all share important similarities when contrasted with the Gospel of John, Erhman believes they corroborate each other and are therefore more historically accurate.

Furthermore, biblical scholars disagree on whether the New Testament should be taken as a historically accurate account of Christ's life in the first place. Those who question Christ’s claims to divinity point out that the gospels were written several decades after Christ's death and in Greek, a language neither Christ nor his original followers would have spoken. Therefore, they were first passed down as oral traditions and may have taken on the characteristics of a legend.

That said, defenders of Lewis's trilemma argue that the gospels should be taken as historically accurate accounts. The first argument is that the gospels are the divinely inspired word of God, and therefore must be accurate. Many Christian denominations hold that scripture is inerrant—meaning none of the gospels can be wrong.

Defenders also argue that there is strong historical evidence that Christ claimed divinity. They highlight evidence from Roman historical documents showing that Christ was a real person, and that in scripture he exhorts his followers to accurately pass on his teachings. Defenders also argue that Christ’s actions were aligned with a perception of divinity. Christ claimed the ability to forgive all sins, which only God could do according to Jewish tradition at the time.

Christ’s Example of Surrender

Lewis argues that Christ is God, and reminds readers that in traditional Christian teaching, Christ lived in human form on Earth—therefore, Christ is simultaneously human and God. Lewis asserts that Christ's dual nature allows him to set an example of perfect surrender. He lays out the following argument.

• Humans are not able to surrender perfectly, because they are imperfect by nature, and surrender is hard. Only God is perfect.
• Even though God is perfect, God is unable to surrender. Lewis writes that one can only truly surrender to something superior, and nothing is superior to God. Therefore, God cannot provide an example of surrender.
• Therefore, only Christ is able to provide an example of perfect surrender. He is able to surrender perfectly because he is God, and he is able to surrender at all because he is human.

Have Christians Always Believed in Christ’s Dual Nature?

Lewis's argument that Christ provides a perfect example of surrender rests on Christ's dual nature: Christ is both human and God, according to mainline Christian teaching. However, it's worth considering that in the earliest years of Christianity, not all Christian sects agreed on Christ's dual nature. A variety of interpretations of Christ arose before the early ecumenical councils sought to standardize Christian belief. Here we'll discuss two early alternatives.

Human but not divine: Some early Christian sects held that Christ was born a regular person, but because of his good deeds, God chose him to become the Messiah. This view is mostly associated with the Ebionites, an early sect of Jewish Christians who followed Christ's teachings alongside traditional Hebrew commandments.

Divine but not human: Other early Christians believed that Christ was in fact God coming to Earth, but that he only appeared human to his followers. This view is associated with Gnostic Christians who rejected the idea that Christ died or suffered on the cross.

Following Christ’s Example

Lewis argues that the purpose of Christian worship is to become more Christlike. While you can never be divine like Christ, you can still follow his human example of surrendering to God's moral laws. This surrender means you will become increasingly Christlike to the best of your human ability.

(Shortform note: Many spiritual traditions confirm the goal of becoming Christlike through religious practices. However, this can do more than simply make you a more virtuous person. In The Untethered Soul, the spiritual teacher Michael Singer writes that Christ's example revealed a divine and inexhaustible love. He argues that by welcoming that divine love into your heart, you join with God in a divine union, bringing you closer to the source of all goodness in life.)