Karl Marx is best known for his Communist Manifesto and for having a fantastic face full of hair rivaled only by his co-conspirator Friedrich Engels, but before he was a socialist, he was an atheist. His later work gave little explicit commentary on religion, largely because the roots of the ills of his society were economic and not religious. Religion, according to Marx, was merely a symptom to those ills, so to treat it would be to act as one removed from the real problem.
For Marx, religion was an enslaver. Servility and submission to authority were the poles of his apathy for religion. But even more than religion as ideology, it was the nineteenth-century church that pushed him over the edge. The church of Marx’s day was kind in its steely way, but it was paternalistic in its authoritarianism. The overriding emotion of the churchgoers of his day was fear of God, guilt for sins, and a servile submission to rules, as well as individualism in piety. This led to fear becoming cowardice, guilt becoming abasement, obedience becoming servility, and individualism becoming egotism. Humanity is free and self-determined and takes as its guide reason alone. It came down to this: freedom versus servility and reason versus authority. These were the shapers of Marx’s atheism. He was not out to destroy God, but to establish free people.
Marx was highly influenced by Feuerbach who said that religion was a projection and an abstraction. Primitive humans projected their fears onto a personified sun or sea or mountain and this became God. Now we project love, power, and all our best traits onto an imagined God. We have given away all our best attributes to an imagined God, thereby alienating ourselves from our true worth.
If atheism was an abstraction, communism was not; it was a praxis–a plan of action. The philanthropy of the former was abstract (unreal) because it was not a praxis; the philanthropy of the latter was real because it was an orientation to action. Atheism was merely the reality factor in one’s assumptions.