Alasdair MacIntyre, a leading moral philosopher in the English speaking world, was from his earliest intellectual formation influenced profoundly both by Christianity and Marxism. MacIntyre argues that Marxism has religious roots, in that it gains its vision of the good life of peace and reconciliation from Christianity, mediated by Hegel, but makes this life historically concrete. The article views MacIntyre's early intellectual career as a case study in the productive tension generated by an analysis of the connections between Christianity and Marxism. It is suggested that by examining the similarities and differences of these two traditions, MacIntyre points to the sources of radicalism that lie at the apparently conservative heart of western culture and reveals aspects of the continuing significance of this culture's religious background. He also points to the difficulties both traditions have in engaging with modern liberal culture.