1511-1553. Anti-Trinitarian theologian and physician. Born in Spain of a pious family, he studied the biblical languages as well as mathematics, philosophy, theology, and law at the universities of Zaragoza and Toulouse, then went as a secretary to Charles V's confessor. He left the imperial court for Basle, then for Strasbourg where he met [[Martin Bucer]]* and possibly some of the Anabaptist leaders. These contacts stimulated his early radical theological ideas.
Servetus came to believe that in order to convert the Moors and Jews, the Christian teaching of the Trinity would have to be reinterpreted. He decided that the most serious error involved in Trinitarian doctrine was the belief in the eternal existence of the Son. He expressed his ideas in several books (1531-32), which led to attacks on his work by orthodox theologians. To avoid further trouble he adopted a disguise and began a second career as a physician. After studying at Lyons, he published a description of the pulmonary circulation of the blood and worked on geography and astrology. He also worked for a time in Vienne as physician to the archbishop and returned to his study of theology. Repeating his earlier attacks on the doctrine of the Trinity, he also rejected infant baptism, while proclaiming a christocentric pantheism developed from Neoplatonic, Franciscan, and Cabalistic elements.
In answer to Calvin's Institutes of the Christian Religion he wrote Restitutio Christianismi (1553). He was arrested and condemned by the Inquisition in Vienne, but escaped and went to Geneva. Again he was arrested and condemned, and this time he was burnt. His execution provoked a controversy over toleration of religious differences.
See E.M. Wilbur, A History of Unitarianism (2 vols., 1945-52), and R.H. Bainton, Hunted Heretic: The Life and Death of [[Michael Servetus]] (1953).