Unitarianism is a system of Christian belief that rejects the Trinity and the divinity of Christ in favor of the single personality of the Godhead. Unitarianism is more radical in its anti-Trinitarianism than Arianism. Though the term was not used in English until the 1680s, and Unitarianism was not legally tolerated as a religious denomination until the early 19th century, it had its origins in 16th- and 17th-century Polish Socinianism, from Fausto Sozzini (1539 1604), known as Socinus. Socinianism was sometimes used as an equivalent label.
John Biddle (1615/16-62), regarded as the father of English Unitarianism, published Socinian tracts in the 1650s. In the 18th century Dissenting congregations, particularly the English Presbyterians turned first to Arian and then to Unitarian views.
Joseph Priestley in his Appeal to the Serious and Candid Professors of Christianity (1770) defended Unitarian principles, and in 1774 Theophilus Lindsey (1723–1808) formed the first Unitarian denomination, opening the Essex Street Chapel in London. Both Priestley and his friend Richard Price became original members of the Unitarian Society in 1791.
S. T. Coleridge briefly contemplated becoming a Unitarian minister. In the 19th century, James Martineau influenced the organization of the Unitarian body in England and Ireland and led the development of rational Unitarianism. Elizabeth Gaskell’s fiction is imbued with Unitarian values.