Dostoevsky 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. He can’t start making excuses for himself

Dostoiévski escreveu: «Se Deus não existisse, tudo seria permitido.» Aí se situa o ponto de partida do existencialismo. Com efeito, tudo é permitido se Deus não existe, fica o homem, por conseguinte, abandonado, já que não encontra em si, nem fora de si uma possibilidade a que se apegue. Antes de mais nada, não há desculpas para ele. Se, com efeito, a existência precede a essência, não será nunca possível referir uma explicação a uma natureza humana dada e imutável; por outras palavras, não há determinismo, o homem é livre, o homem é liberdade. Se, por outro lado, Deus não existe, não encotnramos diante de nós valores ou imposições que nos legitimam o comportamento. Assim, não temos nem atrás de nós, nem diante de nós, no domínio luminoso dos valores, justificações ou desculpas. Estamos sós e sem desculpas.

But if man is free to define for himself the conditions of a life which is valid in his own eyes, can he not choose whatever he likes and act however he likes? Dostoievsky asserted, “If God does not exist, everything is permitted.” Today’s believers use this formula for their own advantage. To re-establish man at the heart of his destiny is, they claim, to repudiate all ethics. However, far from God’s absence authorizing all license, the contrary is the case, because man is abandoned on the earth, because his acts are definitive, absolute engagements. He bears the responsibility for a world which is not the work of a strange power, but of himself, where his defeats are inscribed, and his victories as well.

L'existentialiste, au contraire, pense qu'il est très gênant que Dieu n'existe pas, car avec lui disparaît toute possibilité de trouver des valeurs dans un ciel intelligible; il ne peut plus y avoir de bien a priori, puisqu'il n'y a pas de conscience infinie et parfaite pour le penser; il n'est écrit nulle part que le bien existe, qu'il faut être honnête, qu'il ne faut pas mentir, puisque précisément nous sommes sur un plan où il y a seulement des hommes.

Atheistic existentialism, of which I am a representative, declares with greater consistency that if God does not exist there is at least one being whose existence comes before its essence, a being which exists before it can be defined by any conception of it. That being is man....

Existentialism is not atheist in the sense that it would exhaust itself in demonstrations of the non-existence of God. It declares, rather, that even if God existed that would make no difference from its point of view. Not that we believe God does exist, but we think that the real problem is not that of His existence; what man needs is to find himself again and to understand that nothing can save him from himself, not even a valid proof of the existence of God.

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.

If existence really does precede essence, there is no explaining things away by reference to a fixed and given human nature. In other words, there is no determinism, man is free, man is freedom. On the other hand, if God does not exist, we find no values or commands to turn to which legitimize our conduct. So, in the bright realm of values, we have no excuse behind us, nor justification before us. We are alone, with no excuses.

Without God all things are permitted.

God is necessary, and therefore must exist... But I know that he does not and cannot exist... Don't you understand that a man with these two thoughts cannot go on living?

If God did not exist, it would be necessary to invent him.

If God really existed, it would be necessary to abolish Him.

He who denies the existence of God, has some reason for wishing that God did not exist.

"God's only excuse is that He doesn't exist," remarked Voltaire after a natural disaster that killed many people. Nietzsche loved this quote and wished he'd coined it!