Flatbush Unitarian Church (Brooklyn, New York, N.Y.).

Although the doctrines of Unitarianism come from 17th century Europe, Unitarianism in America during the 19th century was influenced by several American theologians including Boston based preacher William Ellery Channing (1780-1842). Channing was one of the first theologians to introduce the principles of Unitarianism to New Yorkers.

In 1819, in response to an address given by Channing in the City of New York, the first Unitarian church was established in the city. Originally formed as the First Congregational Church (later renamed Church of the Devine Unity and finally, All Souls Church) its first meeting house was located on Chambers Street in today's lower Manhattan.

The first Unitarian gathering was held in Brooklyn in 1833. Between 1835 and 1900 numerous Unitarian societies and churches were established in Brooklyn including the First Unitarian Congregational Society of Brooklyn, 1835; the Female Samaritan Society, 1838; the Second Unitarian Congregational Society, 1840; the Church of the Saviour, 1844; All Souls Universalist Church of Brooklyn, 1845; the Second Unitarian Congregation of Brooklyn, 1852; the Third Unitarian Congregational Society of Brooklyn, 1867; Unity Church, 1868; and Flatbush Unitarian Church (also known as the Fourth Unitarian Church of Brooklyn), 1900.

Although Unitarian beliefs differed somewhat amongst groups and churches, commonly shared beliefs included: the ability of humans to exercise free will; that rational, scientific, and philosophical thought could coexist with religious belief; the life of Jesus should be used as an example and guide for individuals to model their lives on; that no one religion could claim theological truth; and that the Bible was open to interpretation because it was a book of literature written by humans. Finally, Unitarians rejected the doctrines of the trinity, predestination, original sin, and eternal damnation. The Universalists main doctrine was the belief in universal salvation.

Originally two separate denominations in America, the Unitarian Church and Universalist Church merged in 1961 forming today's Unitarian Universalist Association.