The quotation, in context, reads as follows (emphasis added):
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.
The abolition of religion as the illusory happiness of the people is the demand for their real happiness. To call on them to give up their illusions about their condition is to call on them to give up a condition that requires illusions. The criticism of religion is, therefore, in embryo, the criticism of that vale of tears of which religion is the halo.[2]
Meaning[ edit]
Marx was making a structural functionalism argument about religion, and particularly about organized religion.[3][4] Marx believed that religion had certain practical functions in society that were similar to the function of opium in a sick or injured person: it reduced people's immediate suffering and provided them with pleasant illusions, but it also reduced their energy and their willingness to confront the oppressive, heartless, and soulless reality that capitalism had forced them into.
扩展阅读：
https://www.zhihu.com/question/31402039
该如何理解马克思说的“宗教是人民的鸦片”这句话？