In Book One of Mere Christianity, C. S. Lewis attempts to use reason and logic to prove the existence of God—in the sense of an all-powerful, non-material being—and later to argue for the divinity of Jesus Christ. These two arguments—the so-called “argument from morality” and the “Christian trilemma”—are two of the most famous aspects of the book, and reflect Lewis’s overall project to justify Christianity through logic—a project that, by Lewis’s own admission, is important, and yet can only go so far toward convincing people to embrace Christianity.
Lewis begins Book One of Mere Christianity by arguing that morality is a “real” thing; in other words, that it exists independent of humanity, and is the same to all human beings across time. He offers many arguments for why morality must be universal and not a human construct: for instance, across human history, moral codes have been strikingly similar, at least on a fundamental level (for instance, Confucius, Lao Tzu, and Christ all said that humans should treat other people the way they would want to be treated). Having argued that morality is universal and not a human construct, Lewis further argues that the existence of a universal, unchanging morality implies the existence of a God—an omnipotent, spiritual being. It’s improbable that a universal, abstract law of right and wrong would come into existence accidentally; so it appears to follow that there must be a being who created this law. This being, Lewis further argues, must not be a material being, since the law of right and wrong is not a material thing. Thus, we arrive at the conclusion that there must be a powerful being who creates the laws of right and wrong and interacts with human beings by exposing them to these laws.
Lewis reaches such a conclusion by employing all the steps of a logical argument: premises, a thesis, evidence to support the thesis, and refutations of potential objections to the thesis. However, it must be noted that Lewis’s arguments have been widely criticized, even by people who subscribe to another version of an argument from morality. For instance, some critics have argued that the historical ubiquity of certain moral principles like the “Golden Rule” doesn’t necessarily prove that morality is universal; maybe it just proves that human self-interest hasn’t changed very much in the last five thousand years.
Lewis then builds off of his argument from morality by arguing—again, with a certain amount of logical support—that Jesus Christ was a divine being who came to Earth to teach humans to achieve salvation. Lewis has used the argument from morality to show that there is an all-powerful, moral being; now, he proposes that Christ was the human embodiment of that all-powerful moral being. To test his own proposition, Lewis studies Christ’s teachings, as recorded in the Bible, and points out that Christ (who claimed to be able to forgive people for their sins) must have been 1) God, 2) a liar, or 3) insane. Lewis rejects the theory, popular during his own lifetime, that Christ was a great moral teacher, but not divine. There is an inherent contradiction, he argues, between Christ’s humanity and his moral teachings—thus, people must either believe that Christ was a man, or that he was a great moral teacher, but not both.
Lewis’s analysis of the Christian trilemma (i.e., that Christ was either God, lying, or insane) illustrates the strengths and the limitations of using logic to argue for Christian. Notice that Lewis does not use logic to prove that Christ must have been divine; instead, he uses logic to disprove the hypothesis that Christ was human and just another great moral teacher. In a similar sense, the argument from morality is not an argument for Christianity; only for the existence of some kind of powerful being—to believe in a Christian God requires a further leap of faith. In general, logic and reason are—by Lewis’s own admission—necessary but insufficient for Christianity. Logic can set readers on the right path toward Christianity, but it cannot by itself convince readers to convert to Christianity. By definition, faith in God is unreasonable—thus, all good Christians must make the deeply personal choice to embrace their religion, independent of logic or reason.
Morality, Religion, and Reason ThemeTracker
Morality, Religion, and Reason Quotes in Mere Christianity
It looks, in fact, very much as if both parties had in mind some kind of Law or Rule of fair play or decent behavior or morality or whatever you like to call it, about which they really agreed […] If they had not, they might, of course, fight like animals, but they could not quarrel in the human sense of the word. Quarrelling means trying to show that the other man is in the wrong. And there would be no sense in trying to do that unless you and he had some sort of agreement as to what Right and Wrong are.
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.
Of course, I quite agree that the Christian religion is, in the long run, a thing of unspeakable comfort. But it does not begin in comfort; it begins in the dismay I have been describing, and it is no use at all trying to go on to that comfort without first going through that dismay.
For Christianity is a fighting religion. It thinks God made the world—that space and time, heat and cold, and all the colors and tastes, and all the animals and vegetables, are things that God 'made up out of His head' as a man makes up a story. But it also thinks that a great many things have gone wrong with the world that God made and that God insists, and insists very loudly, on our putting them right again.
Atheism turns out to be too simple. If the whole universe has no meaning, we should never have found out that it has no meaning: just as, if there were no light in the universe and therefore no creatures with eyes, we should never know it was dark. Dark would be a word without meaning.
Reality, in fact, is usually something you could not have guessed. That is one of the reasons I believe Christianity. It is a religion you could not have guessed. If it offered us just the kind of universe we had always expected, I should feel we were making it up.
Badness cannot succeed even in being bad in the same way in which goodness is good. Goodness is, so to speak, itself: badness is only spoiled goodness. And there must be something good first before it can be spoiled.
A man who was merely a man and said the sort of things Jesus said would not be a great moral teacher. He would either be a lunatic—on a level with the man who says he is a poached egg—or else he would be the Devil of Hell. You must make your choice. Either this man was, and is, the Son of God: or else a madman or something worse.
What [science textbooks] do when they want to explain the atom, or something of that sort, is to give you a description out of which you can make a mental picture. But then they warn you that this picture is not what the scientists actually believe. What the scientists believe is a mathematical formula. The pictures are there only to help you understand the formula. They are not really true in the way the formula is; they do not give you the real thing but only something more or less like it. They are only meant to help, and if they do not help you can drop them. The thing itself cannot be pictured, it can only be expressed mathematically. We are in the same boat here.
There are three things that spread the Christ-life to us: baptism, belief, and that mysterious action which different Christians call by different names—Holy Communion, the Mass, the Lord's Supper. At least, those are the three ordinary methods […] I am not saying anything about which of these three things is the most essential. My Methodist friend would like me to say more about belief and less (in proportion) about the other two. But I am not going into that. Anyone who professes to teach you Christian doctrine will, in fact, tell you to use all three, and that is enough for our present purpose.
Let the thrill go—let it die away—go on through that period of death into the quieter interest and happiness that follow—and you will find you are living in a world of new thrills all the time. […] It is much better fun to learn to swim than to go on endlessly (and hopelessly) trying to get back the feeling you had when you first went paddling as a small boy.