The course aims to explore the ways in which the Church has fought, contained, and repressed the phenomenon of heterodoxy within itself. From the first doctrinal constructions and syntheses in the times of the Church Fathers to the interventions of the Congregation for the Doctrine of the Faith in the 20th century, the course aims to identify the lines of continuity and rupture in the way of managing the heretical phenomenon. From a historical point of view, the course will explore some relevant elements: the evolution of the concept of heresy, the forms of repression of it, or the penalties imposed on heretics, and the forms of repression. Particular attention will be paid to the genesis and development of the Roman Inquisition – in the context of the birth of the other modern Inquisitions – and its “little sister”, the Congregation of the Index, examining their norms, procedures, and fields of intervention. The course will also explore some cases that are particularly present in popular culture: the Inquisition; the case of Giordano Bruno, of Galileo; the management of the case of witches; the fight against Protestants; the censorship of books; the containment of some phenomena: Jansenism, Old Catholics, modernism, and Liberation Theology.