This work analyzes the emergence and development of a leftist Christianity in Chile, concentrating in the experience of a clerical group called "Christians for Socialism" (Cristianos por el Socialismo, CpS). This analysis transcends Chilean frontiers, trying to understand the broader political radicalization the Catholic Church lived in the late 1960s. The Chilean experience, however, had its own originality: revolutionary priests emerged in the middle of Popular Unity project, a process of building socialism by democratic means in a Cold War context.

From an experiential point of view, this work analyzes the emergence of Christians for Socialism highlighting the religious evolution that some churchmen and churchwomen experienced. This work understands Christians for Socialism as a final stage of a long-term religious evolution, that could be summarized in three elements: a new conception of a Catholic social change; a new phase for social ministry; and new meanings of poverty and the poor.

This work also illuminates the comprehension of leftist Christianity as a global phenomenon. This is a history of a vast network of Catholic clerical agents that in a Cold War global context, laid the foundations for a deep social change in Latin America. This is a history of the convergence between Catholicism and the social sciences from the late Fifties on in Latin America, its underdevelopment and poverty. But also, this is a study of the personal dilemma that some pastoral agents experienced, mainly related to the way in which they understood their temporal and spiritual mission. This study understands the re-adaptation of the fields of religion and politics and, specifically, to a re-adaptation of the role of priests in modern world. This study, finally, digs deep into the experience of some pastoral agents with the poor. These experiences, in some cases, triggered a new conception of their pastoral role, and finally of the temporal role of the Catholic Church as well. The subsequent temporal commitments, with some revolutionary projects or paths, responded to this internal process.