What does it mean when marx says that religion is an upium to the people

"In Germany, Marx writes, ‘the critique of religion is essentially completed’. Thus the problem is how to go beyond it. Marx’s first step is to explain the significance of that critique, as he understands it.

The world of religion is a reflection of a particular form of society: ‘This state, this society, produce religion, which is an inverted world-consciousness, because they are an inverted world’. That is to say, only an inverted, secular world would produce religion as its offshoot. In religious belief, Man finds himself reflected in the ‘fantastic reality of heaven’, whilst he can find only ‘the semblance of himself, only a nonhuman being’ in this world. Religion thus provides a realm in which individuals can realize themselves, at least partially, given that full and adequate self-realization is not possible in the profane world. In this way, religion preserves the social order of which it is a by-product, both by deflecting attention from its defects and by providing a partial escape from it. In Marx’s famous words, ‘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’.

Thus religion and the form of life associated with it are open to criticism at three points. (1) There is, first, the impoverished and distorted world of which religion is a by-product. (2) There is the way in which the image of reality produced by religion is falsely transfigured. (3) Finally, there is the failure by human beings to recognize the fact that religion has its origins in mundane reality.

It is this last element towards which the critique of religion is directed. Critique of religion connects religion back to its unacknowledged origins in social existence. Yet this is not enough. The critique of religion, inasmuch as it is a call to people to abandon their illusions, is also, according to Marx, ‘the call to abandon a condition that requires illusions’. By itself the critique of religion cannot remove the distortion and impoverishment of the world from which religion arises. This is of course Marx’s real project, for which the criticism of religion has merely prepared the ground.

Once the criticism of religion has done its work, philosophy must move on ‘to unmask human self-alienation in its secular forms’. The critique of religion ends, Marx says, ‘in the doctrine that man is the supreme being for man; thus it ends with the categorical imperative to overthrow all conditions in which man is a debased, enslaved, neglected, contemptible being’"

ROSEN, MICHAEL (1998, 2003). Marx, Karl. In E. Craig (Ed.), Routledge Encyclopedia of Philosophy. London: Routledge. Retrieved April 17, 2013, from http://www.rep.routledge.com/article/DC051SECT3