Full Idea
For the atheist existentialist there disappears with God all possibility of finding values in an intelligible heaven. (Dostoevsky wrote "If God did not exist, everything would be permitted").
Gist of Idea
Without God there is no intelligibility or value
Source
Jean-Paul Sartre (Existentialism and Humanism [1945], p.33)
Book Reference
Sartre,Jean-Paul: 'Existentialism and Humanism', ed/tr. Mairet,Philip [Methuen 1980], p.33