Marxism appears repeatedly in Pope Benedict´s theology and teaching as a permanent enemy that Christianity must oppose without any possibilities of conciliation between them. However, what underlies this decisive rejection? To answer this question we look further into Joseph Ratzinger´s perspective starting with some of his theological writings (before the pontificate) followed by three of his encyclicals, the high point of his papal teaching (Deus caritas est, Spe salvi e Caritas in veritate). We argue that Benedict XVI's criticism, prior to being purely theological (or doctrinal), is philosophical, based on rationality and not in the faith professed by the Church, allowing him to treat marxism not simply as a political program that goes a...