Marxism is an economic ideal that doesn't really work, it has little directly to do with atheism, which is simply a lack of belief in any deity.
Not according to Marx:
the criticism of religion is the prerequisite of all criticism...
It is, therefore, the task of history, once the other-world of truth has vanished, to establish the truth of this world. It is the immediate task of philosophy, which is in the service of history, to unmask self-estrangement in its unholy forms once the holy form of human self-estrangement has been unmasked. Thus, the criticism of Heaven turns into the criticism of Earth, the criticism of religion into the criticism of law, and the criticism of theology into the criticism of politics.
The only liberation of Germany which is practically possible is liberation from the point of view of that theory which declares man to be the supreme being for man
Marx - A Contribution to the Critique of Hegel’s Philosophy of Right
For Marx it's similar to a fundamentalist Muslim rejecting all other 'false' religions. If religions are false, then their traditions and moral codes are based on lies and creators of a false consciousness. When there is 'One True Path' that leads to utopia, anything that takes you away from this is an abomination. (
Marx: therefore it reaches the categorical imperative of overthrowing all relationships in which man is a degraded, enslaved, abandoned, contemptible being... The abolition of religion as the illusory happiness of the people is the demand for their real happiness.)
The role of atheism in Marxism is similar to the role of God in classical monotheism On its own god belief means little, but take it away from the religion and it starts to collapse. As monotheism requires a God, Marxism requires no god: (
Marx: The criticism of religion leads to the doctrine according to which man is, for man, the supreme being.")
While classical monotheist religions generally understood the impossibility of eradicating 'false' teachings, and the 'perfection' of humanity without divine intervention during the eschaton, Marxism considered this achievable via human endeavour. The eradication of religions and god-beliefs is thus a necessity.
Usual disclaimer: Obviously atheism is not "responsible" for Marxism and it doesn't make atheism "bad", but it was essential for Marxism.
The suppression of religion had more to do with trying to end the idea of divine right of kings, and of course Stalin's paranoia could not have allowed any organisation to rival the state machine, as he wanted absolute power.
Not according to Marxist-Leninst philosophy:
Lenin: "Atheism is a natural and inseparable part of Marxism"
Leon Trotsky: “We must rid ourselves once and for all of the Quaker-Papist babble about the sanctity of human life”.
Yemelyan Yaroslavsky: It is our duty to destroy every religious world-concept... If the destruction of ten million human beings, as happened in the last war, should be necessary for the triumph of one definite class, then that must be done and it will be done.
Nikolai Bukharin: Many weak-kneed communists reason as follows: 'Religion does not prevent my being a communist. I believe both in God and in communism. My faith in God does not hinder me from fighting for the cause of the proletarian revolution.'
This train of thought is radically false. Religion and communism are incompatible, both theoretically and practically.
Every communist must regard social phenomena (the relationships between human beings, revolutions, wars, etc.) as processes which occur in accordance with definite laws. The laws of social development have been fully established by scientific communism on the basis of the theory of historical materialism which we owe to our great teachers Karl Marx and Friedrich Engels. This theory explains that social development is not brought about by any kind of supernatural forces. Nay more. The same theory has demonstrated that the very idea of God and of supernatural powers arises at a definite stage in human history, and at another definite stage begins to disappear as a childish notion which finds no confirmation in practical life and in the struggle between man and nature...
Scientific communism, in its judgements concerning natural phenomena, is guided by the data of the natural sciences, which are in irreconcilable conflict with all religious imaginings.
When you believe you are creating a utopia, the ends justify the means. With a materialistic worldview and man as the 'supreme being' there was no sanctity of human life', just a ruthless utilitarian outlook where the greater good is whatever further the revolutionary cause.
"What violence would you not commit to exterminate violence?" (Bertolt Brecht)
Per religion, it's more than the destruction of their power bases though, it is their total eradication. They cannot exist in the final stage of Communism: "
It is our duty to destroy every religious world-concept"