Karl Marx’s atheism is well known, even if his criticism of religion has more often than not been misconstrued. The distortions to his critical theory of religion stem from common misperceptions of the philosophical, political, and cultural context in which key statements on religion were formulated – and exacerbated by interpretations of his work that trade in anachronisms. The subsequent history of Marxism’s attitude to religion (and Marxism’s reading of Marx’s texts on religion), has itself been shaped by the different contexts in which Marxism has been either a revolutionary social movement, or a state ideology in which atheism has become part of the Marxist confession of faith. Marx’s atheism is multifaceted; some aspects are relatively banal, others appear either antiquated or naive; the criticism of religion formed at the nexus of his politics and dialectical thinking continue to provide a stimulating starting point and sounding board for thinking about religion today.