This article is dedicated to the metamorphosis of the concept of libertinism. In recent years, historical investigation has identified Florentine and Sienese Republicanism as the first attestation of the terms «libertine» and «libertinism», thus giving the concept an initial political origin. The new acquisition raises the problem of the relationship between this initial political meaning of the terms «libertine» and «libertinism» and the subsequent one linked to religious criticism. Reconstructing the genealogy of Niccolò Amerighi, Vittorio Frajese identifies the trial brought by the Inquisition of Siena against Amerighi and the Roman astrologer Flaminio Fabrizi as the link thus far documented between the two cultures and the corresponding meanings of the term. Examining the other meaning taken on by the concept of «libertine» in the Christian area, Frajese analyzes the «libertine» theology attacked by John Calvin in 1545, advancing the hypothesis that it constitutes a manifestation of the latomic life conducted in the Middle Ages by the Protochristian oral traditions as borne witness to by Origen, Clement of Alexandria and Irenaeus. According to the author, the points of intersection between the two traditions remain to be determined.