SOZZINI, FAUSTO PAVOLO (1539–1604), was an antitrinitarian theologian, known in Latin as Faustus Socinus. Sozzini was born in Siena on December 5, 1539. When his uncles fell under suspicion of heresy, and the Inquisition threatened the Sozzini family, Sozzini left Italy on April 21, 1561, for Lyons, France. After the death of his uncle Lelio Sozzini on May 14, 1562, Fausto acquired Lelio's manuscripts, which decisively turned his interests from literary studies to religious studies, specifically to doctrinal reform. His Explicatio primae partis primi capitis Ioannis (Explanation of the First Part of the First Chapter of John's Gospel), written in 1562 during his stay in Zurich and Basel, developed more fully Lelio's view of Christ as the person who revealed God's new creation by his teachings and his life.

Sozzini returned to Italy in 1563, where he served at the court of Cosimo I, duke of Florence (later grand duke of Tuscany). In...