Karl Marx in Deutsch-Französische Jahrbücher, February, 1844

For Germany, the criticism of religion has been essentially completed, and the criticism of religion is the prerequisite of all criticism.

The profane existence of error is compromised as soon as its heavenly oratio pro aris et focis [“speech for the altars and hearths”] has been refuted. Man, who has found only the reflection of himself in the fantastic reality of heaven, where he sought a superman, will no longer feel disposed to find the mere appearance of himself, the non-man [Unmensch], where he seeks and must seek his true reality.

The foundation of irreligious criticism is: Man makes religion, religion does not make man. Religion is, indeed, the self-consciousness and self-esteem of man who has either not yet won through to himself, or has already lost himself again. But man is no abstract being squatting outside the world. Man is the world of man – state, society. This state and this society produce religion, which is an inverted consciousness of the world, because they are an inverted world. Religion is the general theory of this world, its encyclopaedic compendium, its logic in popular form, its spiritual point d’honneur, its enthusiasm, its moral sanction, its solemn complement, and its universal basis of consolation and justification. It is the fantastic realization of the human essence since the human essence has not acquired any true reality. The struggle against religion is, therefore, indirectly the struggle against that world whose spiritual aroma is religion.

Religious suffering is, at one and the same time, the expression of real suffering and a protest against real suffering. Religion is the sigh of the oppressed creature, the heart of a heartless world, and the soul of soulless conditions. It is the opium of the people.