Camus insists that he is an absurdist, not an existentialist. OK, but it is important to figure out what he means. Camus thinks a Christian can be an absurdist. I don't. I do think that absurdism is the leading alternative not only to Christianity, but religion.  Religion is said to be based on faith, as it is.  Camus' absurdism is based on a particular heroic ideal, a man who faces the truth head on, as if it were that simple.

The world is not absurd

I said that the world is absurd, but I was too hasty. This world in itself is not reasonable, that is all that can be said.  What is absurd is the confrontation of the irrational world and the wild longing for clarity whose call echoes in the human heart. The absurd depends as much on man as on the world (Myth of Sisyphus, 21)

Though Camus writes about clarity (clarté), that could be misleading.  What he means is that humans long for this world to be where we belong, that we are placed here for a reason, even if we lack clarity about it.  This belief underlies the Judeo-Christian tradition.  The absurd says there is no purpose; we just happen to be here.

The Plague is about what it means to live without this underlying assumption.  It means that humanity's job is to fight creation as we have found it (compare Genesis 1:28).  We fight creation best when we work together.  Absurdism is not a doctrine of individualism.  If you remember The Plague, you will recall that even the absurd M. Grand, who spent years rewriting the first sentence of his novel (he never gets any further), is an everyday hero, volunteering to serve in the Sanitary Squad at some risk to himself.*  Camus' point seems to be that even if the Sanitary Squad accomplished little in fighting the plague, it is noble for humans to work together to make this world a more fit place for humans to live.

From this perspective, religion is a communal creation, a story people tell each other about why we are meant to be here.  One reason religion is effective is because it is reinforced with shared rituals, another is because most of us learn it as children.  By the way, this account of religion, which is mine, says nothing about whether God exists.  We have religion, or we don't.  God is in his heaven, or he isn't.  The first sentence is logically unrelated to the second. 

There is only this life

An absurd sensitivity requires that there be only this life.  If a Christian accepts this, he or she can also be an absurdist.  So says Camus (Sisyphus, 112).  First of all, a Christian couldn't accept this.  Second, Christianity isn't just, or even primarily, about an afterlife.  Christianity denies the fundamental tenet of absurdism, asserting that we are meant to be here, and God provides the answer as to why, even if his answer isn't always transparent.  God also tells us how we should live.  None of this is compatible with absurdism.  I have been unable to figure out why Camus says a Christian could be an absurdist, except that he never wanted to completely disavow faith.  In other words, he had nostalgia for Christianity.

A world without appeal

Recognizing the claims of absurdity, many religious thinkers, and Søren Kierkegaard is my favorite, argue that there is a world beyond clarity, reason, and objective truth.  Kierkegaard calls it subjective truth.  We know it through our feelings, our intuition, our desires.  We know that we are in love when we feel it, not when someone measures our endorphin levels, or whatever.  Faith works much the same way.  Love's knowledge is faith's knowledge.

Camus' response is that religious belief requires that we deny observation, logic, and experience.  Religious belief requires "philosophical suicide," as he calls it.  Mass hunger, starvation, disease, and endless war somewhere on this planet every hour of every day, is an experience of a world without appeal, as Camus puts it, a world in which we have to work out our own meaning, as the characters do in The Plague.  Absurdism does not mean not one's life is subjectively absurd, only that its meaning is not given, and so we must find it for ourselves in a world that means only what we put into it.

Hence, what Camus demands of himself is to live solely with what he knows, to accommodate himself to what is, and to bring in nothing that is not certain. He is told that nothing is. But this at least is a certainty. And it is with this that he is concerned: he wants to find out if it is possible to live without appeal (Sisyphus, 53).

Revolt

Camus has an old-fashioned sense of virtue, what the ancient Greeks called arete.  We live best and most nobly when we face the fact of a world without meaning and struggle against it in the way we live, as well as the way we think and feel.  Camus calls this way revolt, and sometimes manliness, echo of an earlier era.

Revolt gives life its value. Spread out over the whole length of a life, it restores its majesty to that life. To a man devoid of blinders, there is no finer sight than that of the intelligence at grips with a reality that transcends it (Sisyphus, 55).

The flaw in Camus' project

Camus courage in facing a world without appeal is admirable.  And yet there is something equally admirable in facing an uncertain world, or rather living with uncertainty.

I want everything to be explained to me or nothing. . .. If one could only say just once: "This is clear," all would be saved (Sisyphus, 27)

Camus understands that clarity is impossible, that it is the cry of a man stranded on the island named absurdity.

But what is absurd is the confrontation of this irrational [world] and the wild longing for clarity whose call echoes in the human heart. (Sisyphus, 21)

But how much difference is there between the clarity of the absurd and the demand that humans accept only what is certain, even if that is nothing but uncertainty itself?  Camus gets certainty by simplifying the world.  For hardly anything in this world is certain, including Camus' assertion that there is only this world (or at least we should live as though this were the case). There are more things in heaven and Earth, Camus, than are dreamt of in your philosophy, as someone famous almost put it. 

Camus risks becoming the scientist he criticizes.  But Kierkegaard was right to begin with.  Much of what we call knowledge is subjective truth.  It is a subjective truth that the noble man is one who lives his life in revolt.  Why not acceptance, even acquiescence?  No reason, it's a preference, just as it is a preference of some to find meaning in God.  If Camus wants to know if he can live a life without appeal, then good for him.  But if that is nobler than some pursuits, such as hypocrisy, it is no more noble than others, including religious pursuits. 

Conclusion

Camus is not writing about what we know, or even what we should believe.  He is writing about his view of "virile behavior" as he calls it.  In many respects I find his view admirable, and agree with it.  It is a contemporary version of what the ancient Greeks called arete, or excellence at being a human.  But it is certainly not the only version of a good or authentic life.