book review

Mere Christianity
by C.S. Lewis
1952, 108 pages

Reviewed by T. Nelson

Since yesterday was the anniversary of C.S. Lewis’s birthday in 1898, I decided to take a break from reading Nietzsche and read that other book religious people are always raving about, though in a more positive way than Nietzsche’s books: C.S. Lewis’ Mere Christianity.

Incidentally, Nietzsche is not what people think. He was, in a sense, the first blogger. He wrote entertainingly and amusingly about music and made brutal social commentary about the future of Germany. He was a brilliant, witty, and insightful writer. He was also provocative, self-contradic­tory, and perhaps a tad egotistic, almost seeing himself as a deity, which might be why his fictional version of Zarathus­tra keeps nattering on about having killed God. He didn’t really mean God was literally dead, only that the West had aband­oned him as a source of belief, which is true.

Believe it or not, C.S. Lewis and Nietzsche are not opposites. They have a lot in common. Mere Christianity consists of a number of arguments for the existence of God and—more interest­ingly—some speculation about what God’s reasoning must have been for sending Jesus to Earth.

Christianity inspired some of the world’s greatest composers, from Bach to Arvo Pärt. I even started taking organ lessons at one time, but stopped when they forced me to play sappy pop music instead of religious stuff like Toccata and Fugue in D Minor.

My approach to Mere Christianity was: okay, I want to hear your arguments. Convince me.

Atheism

Religious people, including Lewis, tend to have simplistic and stereotyped views about atheists:

If you are an atheist you do have to believe that the main point in all the religions of the whole world is simply one huge mistake. If you are a Christian, you are free to think that all these religions, even the queerest ones, contain at least some hint of the truth.

Few atheists think religion is a huge mistake. Most think it evolved along with society and provides psychological benefits. In their opinion, that is not a reason why its claims about factual matters must be true. They also recognize that as with many myths, religions can contain a hint of truth, as in Genesis where the Bible says the universe began with light. That’s reasonably close to the current theory that there was light (among other things) at the begin­ning, even though it was completely blocked for the first 380,000 years and there were no stars for 200,000,000 years.*

The Moral Law argument

The most important reason Lewis thinks God must exist is that our concept of a Moral Law comes from God:

The moment you say that one set of moral ideas can be better than another, you are, in fact, measuring them both by a standard, saying that one of them conforms to the standard more nearly than the other . . . . You are, in fact, comparing them both with some Real Morality, admitting that there is such a thing as a real Right, independent of what people think, and that some people’s ideas get nearer to that real Right than others.

Let’s take this argument apart. Lewis’s hypothet­ical opponent is saying four things:

1. Moral ideas are not handed down from God.

2. One moral idea is better than another.

3. Therefore God doesn’t exist.

4. If God doesn’t exist, the whole of reality is senseless.

To his credit, Lewis doesn’t make the consequentialist argument that some religious people make. This argument says that if moral ideas are invented by humans, then humans will invent harmful moral systems where evil actions are encouraged. This would be bad, the argument goes, so it must not be true.

Lewis’s claim is different: he says that all humans have the same concepts of right and wrong and therefore God must have instilled it in them. His argument is that #2 contradicts #1. But #2 is in the definition of ‘moral value’ so it is automatically true. The real question is: do people all really believe the same thing deep down about right and wrong as Lewis says? I think he is mistaken here: they do not. If so, the rest doesn’t follow.

So, this argument boils down to a raw assertion that there can’t be universal values without a deity. Aversion to murder is one such value. A deity could have programmed us, or maybe it—dare I say—evolved as a way of keeping peace among warlike humans.

Compare that with Nietzsche, who wrote:

For what purpose did God give man revelation? . . . Man cannot of his own accord know what is good and what is evil, that is why God taught man his [God's] will. (The Antichrist, Aph.55)

Granted, you can never be too sure about philosophers—maybe he’s setting up a contrast with the Lawbook of Manu in Hinduism—but in this passage where Nietzsche says these questions are not given to man to decide between true and false, he sounds just like C.S. Lewis.

Claim #4 actually belongs to an entirely different argument, namely the assertion that for reality to make sense, God had to create it in a sensible, logical, and moral way. Lewis states it this way:

If the whole universe has no meaning, we should never have found out that it has no meaning.

The idea that a god put structure, logic, and meaning in the world is something religious people often say, and it’s probably impossible to know the answer.

Positing a universal Moral Law presupposes that humans can’t form a concept of justice on their own. They’d just do whatever got them the most benefit at least cost. But even monkeys and dolphins can do it: they become angry when you treat one monkey preferen­tially and, like humans, they start throwing shit at each other. So can some birds.** A society that didn’t develop moral principles would be a living hell and would self-destruct within decades.

We have examples: Khmer Rouge Cambodia, Nazi Germany, and the Aztecs. The Aztecs thought it was not only desirable but essential to cut out the hearts of virgins and enemies while still alive and eat them. If they didn’t, there would be a drought and their crops would die. Maybe you think the Christian Spaniards were so outraged by this evil that they were justified in bringing down the Aztecs; but the Aztecs’ neighbors, who were the main suppliers of victims, hated them even more, and the Spaniards would certainly all have been eaten if that were not so. And many were.

If right and wrong were intrinsic to the soul, we’d all know it automatically and we could sit back and relax and things like this would just work out.

Next Lewis says the universe (or at least a tiny part of it) seems adequately suited for life. Therefore God exists and created it that way. This is the fine tuning argument, which is a misunderstanding of physics. When that big asteroid turns the Earth into a pool of molten lava, come back and tell me how perfectly suited the Earth was for life.

Forgiveness

In a passage reminiscent of the Narnia massacre (see review at left), Lewis tells us God is utterly ruthless:

If we used [the created universe] as our only clue, then 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).

For God (assuming he existed), sending Jesus to Earth would have been a gamble: What if the humans suspected that instead of feeding 5,000 people with five loaves and two fish they actually meant 5,000 people feeding two fish with five loaves? They’d say the whole religion was based on copy errors, misquotes, and exaggera­tions. In this section, Lewis explains what he thinks.

Lewis starts by saying it makes no sense for humans to say they can forgive sins. But Jesus said that, so Lewis says we’re forced to decide that Jesus was either a madman or lunatic, a devil from hell, or a deity. But there's a false choice here: why are those the only choices? Jesus was obviously well versed in biblical ideas, even to the point of reciting Psalms on the cross. Why couldn’t the part about being God be another metaphor?

No answer. Anyway, the really big question is how all this sin and forgiveness stuff is supposed to work. Christians realized that just having God come to Earth and getting killed for no good reason wouldn’t be a sound basis for a religion. Just dying is bad enough; getting resurrected and then moving to India afterward, as some people claim, would be even worse. So they proposed that the purpose was to redeem the humans from sin. But how would this work? How would sending Jesus to Earth to get killed redeem anybody? C.S. Lewis’s explanation is that repenting is like dying, but Jesus dying is somehow necessary to make it work:

[O]ur attempts at this dying will succeed only if we men share in God’s dying, just as our thinking can succeed only because it is a drop out of the ocean of His intelligence; but we cannot share God’s dying unless God dies; and He cannot die except by being a man. That is the sense in which He pays our debt. [emphasis added; capitalization in the original]

That’s a much-needed attempt at a plausible rationale for the most important event in Christ­ian­ity, namely the appearance of Jesus. And notice how clever it is: you can believe Jesus was nutty as a fruitcake and yet it still sounds reasonably plausible. Of course, you could say repenting is not really like dying at all, so a better explanation is still needed.

That’s as far as Lewis got. But note the similarity with Nietzsche: both of them say God died. Maybe when religious people are done apolo­giz­ing to Nietzsche they can search for that explanation.

Eternal life

The last part is a bit of basic theology. He says the purpose of becoming a Christian is to become a little Christ, by which he means changing from a created thing to a begotten one and thus becoming immortal, which we weren’t before. He writes:

If you want joy, power, peace, eternal life, you must get close to, or even into, the thing that has them. . . . They are a great fountain of energy and beauty spurting up at the very centre of reality. . .

How could a human, which is basically a wild animal that wears clothes, become immortal? My uninformed guess is that it’s like all those plot holes in Harry Potter, where it snows all the time but nobody ever seems to shovel it. Or when they drink polyjuice potion, which changes people to whatever is in it. One of the ingredients is lacewing flies. So why don’t they turn into lacewing flies? Answer: no one knows.

Both Lewis and Nietzsche are really saying the same thing: They both say God died. They just differ in how, why, what to do about it, and what happens afterward. Both talk about things being “beyond good and evil.” C.S. Lewis may have been a better Christian, but there’s no doubt that Nietzsche was a better writer—and badly mis­under­stood by religious people.

Updates

* Photons were created a fraction of a second after the Big Bang. Technically, you could say the universe was “dark” until then. By the first second, a photon’s mean path length was about the width of an atom. Photons were bound to charged particles such as electrons through Compton scattering. The time when this stage ended, about 380,000 years after the Big Bang, is called decoupling. After decoupling, the universe became transparent and photons could propagate as light.

One thing critics of the Bible get wrong is the supposed seven day time scale. (Creationists, who go into contortions to match it up with scientific findings, make the same mistake.) It was obviously intended as a literary trope, like saying “On the first day, Rome was founded; on the second day it became a republic; on the third day it became a dictatorship; and on the fourth day it fell.” It is clearly not a literal time scale.

** Or at least the monkeys do; not sure about dolphins. Birds do this as well: do something that pisses them off, like setting up an owl effigy, and they will dive bomb it continuously.

nov 30, 2025. updated dec 01, 2025. updated and edited for clarity dec 04, 2025. updated dec 10 and dec 14, 2025