To many readers of Orlando Furioso, Ariosto appears to be essentially disinterested in religious matters, a poet who thinks religion and morality should be kept away from literary creation. However, in this paper I will argue that Ariosto, far from being a-religious, or even un-Christian, was deeply engaged with contemporary religious debates. And without understanding this, it is impossible to comprehend Ariosto’s historical location. The author of a 1498 letter to Aldo Manuzio, where he requested Marsilio Ficino’s hermetic books on behalf of his fellow ferrarese literati, Ariosto needs to be read against the background of his own culture: he was walking the roads of Ferrara when Savonarola was preaching and Pomponazzi teaching there; his publisher, Giovanni Mazzocchi, was also the publisher of heterodox literature; his older friends and masters, Celio Calcagnini and Bonaventura Pistofilo, were the first to import Erasmus’s polemics with Luther into Italy; and Orlando Furioso is full of religious allusions and stances. Placing Ariosto and his poem in the context of Ferrarese approaches to Christianity, I will reassess and re-evaluate Ariosto’s positions in regard to religious debates, including the at the time much debated issues of predestination, the original sin and Saint John’s body.