Just a bit more material on Marx's atheism, and how it was essential to his philosophy. Also a bit about the atheism of Soviet Communism too.
"When you presuppose the idea of an objective god, how can you talk of laws which reason produces from itself, since autonomy can be attributed only to an absolutely free being? " Karl Marx, Notes to [Marx's] Dissertation
Basically, who is sovereign, God or man? It must be one or the other, it can't be both.
Marx's position was that if man is not the appropriator and creator of self and self's destiny, and especially if he is not even aware and con scious of himself as the creator of self and self's destiny, then he is non existent. Until man arrives at such a consciousness of self, he is alienated and fragmented. According to Marx, religion is the greatest culprit for instilling into man's consciousness the idea of creation by another - above all by God. Thus through religion man is dispossessed of his creative consciousness. Consequently, he is dispossessed of the chance and ability to create his own self, create his own identity and destiny. Instead man loses consciousness and awareness of self. He becomes like an object, like another commodity regulated by the forces of production and the relations of production.
The Role of Atheism in Marxian Philosophy, Russel P. Moroziuk, Studies in Soviet Thought, Vol. 14, No. 3/4 (Sep. - Dec., 1974),
"chief among these expressions of a 'false consciousness' is religion. Religion is, first of all, a result of historical evolution, a reflection of the economic conditions of a is -like all ideologies - an arm in the class-war and is used to prevent man's progress toward self-realization. This is why Marx felt obliged to come out openly for the total supression of religion and it is this aspect of his atheism which was seized upon by his Marxist-Leninist heirs."
"Lenin's atheism was more instinctive than rational and, at the same time, it was more violent than that of either Marx or Engels... Lenin's militant atheism set the tone for the activities of Marxist-Leninist atheists from his death until the dark days of the Second World War. Practical atheism was the order of the day mainly because the then reigning crown prince of Soviet philosophy, Stalin, had not uttered one theoretical statement on the subject of God and religion. Practical atheism meant schools of atheism, administrative elimination of the clergy, journals and newspapers full of hate-propaganda directed against all believers, atheist museums located in former churches, and numerous other forms of persecution and suppression. But, the main emphasis in this period was on education - an education designed to eliminate religious customs and beliefs... "
Scientific Atheism: An Introduction, Thomas J. Blakeley, Studies in Soviet Thought, Vol. 4, No. 4 (Dec., 1964),