In 1783, the president of Yale College, Ezra Stiles (1727-1795), predicted that three religious denominations--the Congregationalists, the Episcopalians, and the Presbyterians--would dominate the new nation's religious life. His prediction proved to be entirely wrong. A number of older denominations quickly expanded--notably the Baptists, Catholics, and Methodists--and a host of new denominations arose, radically reshaping the religious landscape--Disciples of Christ, Mormons, and separate African American churches.
Unitarianism, the epitome of religious liberalism, was one of many new religious denominations to appear in the early nineteenth century United States. Few religious denominations exerted a stronger influence upon American intellectual life (through such figures as the poets William Cullen Bryant (1794-1878), Henry Wadsworth Longfellow (1807-1882), and James Russell Lowell (1819-1891), and the historian Francis Parkman (1823-1894)) or contributed as many prominent antebellum reformers, including Dorothea Dix (1802-1887), a crusader on behalf of the mentally ill; Samuel Gridley Howe (1801-1876), a staunch advocate for the blind; and the educational reformer Horace Mann (1796-1859)).
A bitter theological conflict, known as the Unitarian Controversy, divided early nineteenth century New England Congregationalists. This conflict pitted theological conservatives who emphasized human depravity against religious liberals who denied there was a scriptural basis for a belief in predestination or original sin. In this letter, Timothy Pickering (1745-1829), a Federalist political leader and Secretary of State under President John Adams, mentions his shift away from orthodox Calvinism to Unitarianism.
It is more than forty years, since, with strong conviction, I renounced the Calvinistic Scheme, in which I had been educated, as utterly incompatible with the perfections of the Deity. But it was not till a later period that the doctrine of the Trinity (which I had never heard controverted in the pulpit) employed my thoughts... and induced me...to reject this dogma, liberalise the creed of Calvin. It has since been the essential article of my faith and practice, to worship only One God, who sent his son to be Savior of the World.