Francesco Pucci was a Florentine heretic who was executed by the Catholic Church in 1597. Since the 1930s, he has been considered by Italian historians to be an important contributor to the development of theories of religious toleration. A close analysis of two texts written by Pucci reveals that his thought was more complex than previously supposed. In a letter to Niccolò Balbani, a Calvinist minister in Geneva, Pucci described his heterodox theology. These views led him to develop a deeply intolerant vision of concord. These theological commitments structured Pucci’s thinking in this period, and they are reflected in his Forma di una republica catholica. The text describes a secret society, which would allow those who followed Pucci’s heterodox beliefs to live freely. The society was conceived as a temporary expedient. Although it contains some tolerant elements, it was designed as a means to secure Pucci’s intolerant vision of concord.