Theological themes that received attention from Renaissance painters centered on the role of images in a devotional setting. Some other contentious issues between Catholics and Protestants appear, such as faith versus works, transubstantiation, the sacraments, the role of the saints, and Mary. Before the challenge raised by the Reformers, the Catholic Church could assume a broad base of common belief and common knowledge, so the art was free of polemics. The exception is the brief period of the hegemony of Savonarola in Florence in the 1490s. Fra Girolamo Savonarola, a fiery Dominican, stepped into the vacuum created when the Medici were expelled and became the leader of the populist, theocratic republic he fashioned with Christ as its head. In response to his attacks on the worldliness of the papacy, he was excommunicated by Pope Alexander VI.