In this book Grado Giovanni Merlo faces an aspect complementary to his well known studies on heresy: the Roman Churchs fight against the heretics. In the authors view this anti-heretical struggle has its decisive climax in the 50 years spanning from the Lateran Council in 1179 up to the 1230s. During this period the theory and practice of the heretical crusade was defined, boundaries between orthodoxy and heresy were distinguished, religious dissent became a political crime and intellectual and political weapons were sharpened, weapons that were to bring about the historic defeat of the heretics even before the Inquisition began. The authors analysis spreads through several layers, from the construction of the ideology to its organisation. The war against the heretics initiated and directed by the Papacy relied on the creation of an image of the anti-heretical fight as an internal crusade, to be combated not only with arms but also with persuasion (through the evangelising work of preaching monks) and was dependent upon a demonisation of the heretics who became the absolute evil, criminals that justified the most violent repression. The Church succeeded in isolating the heretics by robbing them of any place in society, bringing to a close a powerful normalisation action.

Grado Giovanni Merlo teaches History of the Medieval Church and of Heretical Movements at Milan State University.