If Marx had a philosophy it could be best described in his own words as critical materialism as opposed to mechanistic materialism. He believed with Feuerbach that critical materialism would mean the end of metaphysics and religion. Again, Marx regarded materialism as the only valid expression of scientific method. Thus, in a footnote on Page 368, Vol. I of Capital, he refers to a particular method as the only materialistic and, therefore, the only scientific method.
Marx took the world that is man and his relations with nature as they are. Marx then embraced a thoroughgoing naturalism as opposed to the super-naturalism of Hegel and other religious thinkers. He believed that facts are not more real than they are found to be, and do not express some deeper underlying truth. It was because Marx collected his facts and organised the knowledge gained from them on the presupposition that he was dealing with a material world, that his theory can be empirically demonstrated. Because Hegel began with metaphysical as opposed to materialistic assumptions he could offer no empirical guide as to the course of history. He could only assure us that a cosmic self-consciousness would come to pass, but how it would do so he is silent. Even in a brief and sketchy analysis of Marx and Hegel, it can be shown that in outlook and method they were worlds apart.
On the question of religion itself, Marx denied that there was some religious essence in man. Religion itself is a product of social life and it only arises when society has reached a certain stage of development in the division of labour. Like all other forms of culture, it can be critically analysed in a specific social situation, and like all other forms of activity it can be shown to change under the impact of changing conditions. While religion had historic justification in the productive rituals of the past, it serves no useful social purpose today.
Marx also denied that man was endowed with a natural religious sentiment, any more than he is naturally endowed with any other aspect of culture. A religious sense is not the outcome of a timeless abstraction, but the product of social consciousness and bound up with a certain stage of social development. To suppose then that any element of supernaturalism could find a place in Marxism is to invalidate the most basic assumptions of historical materialism. For that reason a belief in super-naturalism is incompatible with Marxism.
From the Socialist Standard, July 1957