"Socinianism," an evangelical rationalist movement, was one of the forerunners of modern Unitarianism. Three phases can be distinguished: (1) the thought of Laelius Socinus (1525–1562) and his nephew Faustus Socinus (1539–1604); (2) the thought and institutions of the Minor (Reformed) Church of Poland, especially as embodied in the Racovian Catechism (1605), which represented a fusion of Faustus's theology with that of the local anti-Trinitarian and partly Anabaptist Minor Church; and (3) the rationalist theology of the Socinianized Minor Church. This last phase was especially important after the Socinianized Minor Church was crushed in Poland in 1658 and the spirit of Socinianism became influential in the Netherlands among the Remonstrants; in the British Isles, in the seventeenth century, among certain Anglican divines and nonconformist intellectuals; and, in the eighteenth century, among the Arminian divines of New England, who were forerunners of the Unitarian congregationalists.

Socinian evangelical rationalism originated from an amalgam of the rationalist humanism of...