This paper focuses on the historical contextualization and analysis of the lecture Marxism and Christianity, delivered by the Peruvian theologian Gustavo Gutiérrez during the Latin American Meeting of Christians for Socialism, held in Santiago de Chile in April 1971. This document—hitherto unpublished—clearly highlights a set of central themes in Gutiérrez's theological reflection within the broader historical transformations experienced by both Chile and Latin America: the legitimacy of revolutionary political action by Christians, the critique of the dualism between the temporal world and the spiritual sphere, the scope and political consequences of liberation, and the role played therein by Marxism, understood simultaneously as a science and as a utopian mobilizing force. According to Gutiérrez, this latter dimension facilitated its convergence with Christianity. In its conclusions, the paper argues both for the coherence of Gutiérrez's positions with the trajectories of convergence between Marxism and Christianity characteristic of the period, and for the significance of secularization awareness within the theological reflection that would come to define liberation theologies.