Existentialism is nothing less than an attempt to draw all the consequences of a coherent atheistic position. It isn't trying to plunge man into despair at all. But if one calls every attitude of unbelief despair, like the Christians, then the word is not being used in its original sense. Existentialism isn't so atheistic that it wears itself out showing that God doesn't exist. Rather, it declares that even if God did exist, that would change nothing. There you've got our point of view. Not that we believe that God exists, but we think that the problem of His existence is not the issue. In this sense, existentialism is optimistic, a doctrine of action, and it is plain dishonesty for Christians to make no distinction between their own despair and ours and then to call us despairing.

If man, as the existentialist conceives him, is indefinable, it is because at first he is nothing. Only afterward will he be something, and he himself will have made what he will be. Thus there is no human nature, since there is no God to conceive it. Not only is man what he conceives himself to be, but he is also only what he wills himself to be after this thrust toward existence.

Three o'clock is always too late or too early for anything you want to do.

The more sand that has escaped from the hourglass of our life, the clearer we should see through it.

Slime is the agony of water.

The existentialist is strongly opposed to a certain kind of secular ethics which would like to abolish God with the least possible expense.

The existentialist...thinks it very distressing that God does not exist, because all possibility of finding values in a heaven of ideas disappears along with Him; there can no longer be a priori of God, since there is no infinite and perfect consciousness to think it. Nowhere is it written that the Good exists, that we must be honest, that we must not lie; because the fact is that we are on a plane where there are only men. Dostoyevsky said, If God didn't exist, everything would be possible. That is the very starting point of existentialism. Indeed, everything is permissible if God does not exist, and as a result man is forlorn, because neither within him nor without does he find anything to cling to.

Man is condemned to be free; because once thrown into the world, he is responsible for everything he does.

Should I betray the proletariat to serve truth or betray truth in the name of the proletariat?

Man is condemned to be free; because once thrown into the world, he is responsible for everything he does.

Everything has been figured out except how to live.

There are two kinds of existentialist; first, those who are Christian...and on the other hand the atheistic existentialists, among whom...I class myself. What they have in common is that they think that existence precedes essence, or, if you prefer, that subjectivity must be the turning point

The existentialist says at once that man is anguish.

Atheistic existentialism...states that if God does not exist, there is at least one being in whom existence precedes essence, a being who exists before he can be defined by any concept and that this being is man, or, as Heidegger says, human reality. What is meant here by saying that existence precedes essence? It means that, first of all, man exists, turns up, appears on the scene, and, only afterwards, defines himself

Quoted from
Jean Paul Sartre