The following text is taken from: Mendelsohn, Jack. Meet the Unitarians & Universalists. Unitarian Universalist Association, 1997.

To find the roots of our religion we must go back to the prophets of ancient Israel and the Socratic tradition of Athens. Modern liberal religion is indebted to these founts of reverence for human dignity and the primacy of ethics in religion.

The Christian origins of our movement are anchored in the moral teachings of Jesus, as exemplified in the Beatitudes and the Sermon on the Mount. Early Christianity was neither Trinitarian nor Unitarian. For nearly three centuries after Jesus’ death, no specific doctrine of this type was enforced as part of an official Christian creed. When doctrinal controversies became too stormy and violent, the Roman Emperor Constantine summoned church leaders to a council in 325 CE where the Nicene Creed was voted into existence. The divinity of Jesus thus became the official orthodoxy of the Christian religion. The Nicene formula declared by a divided vote that Jesus was of the same essential substance as God.

A half century later, at another gathering of church leaders, the General Council of Constantinople, the assembled dignitaries added the Holy Spirit to their formula, thus completing the Trinity. This was the very human manner in which the Trinitarian dogma of “Father, Son, and Holy Spirit” came into existence. From the beginning there were sincere and thoughtful Christians who felt that the essential message of Jesus was being swamped in a sea of metaphysics, but those who could not conscientiously accept the Trinitarian position were expelled, condemned, and martyred as heretics. Nevertheless, a spirit of independent thought and belief continued to flicker through the centuries. The ferment of the Protestant Reformation furnished adventurous opportunities for leaders of a more liberal mind. Some began to question the Trinity, and to call for less rigid religious conceptions and practices. Their cause was immortalized by the shameful burning of Michael Servetus in Switzerland by order of John Calvin. Servetus’ crime was the writing of a book, On the Errors of the Trinity, in which he argued that the Trinity was a grotesque and distracting addition to the true Christian life. Servetus was burned and many others were tortured and slain for expressing personal convictions in opposition to official orthodoxies, but irrepressible ideas were in the air. In Italy, Switzerland, Hungary, Poland, Holland, and England, spokespersons for a liberalized Christianity appeared in ever-increasing numbers. Ministers and entire congregations began to secede from orthodox ranks in rebellion against theological dogmatism.

In 1568, the only Unitarian king in history, John Sigismund of Transylvania, issued the Western world’s first edict of religious freedom. The world’s oldest Unitarian congregation is found in the Transylvanian city of Koloszvár. It left the ranks of orthodoxy in 1568 to follow the leadership of the brilliant reformer Francis David. By 1600, there were more than 400 Unitarian congregations in the surrounding area. Later, in England, the cause of liberal religion was advanced by the powerful advocacy of such people as John Milton, Isaac Newton, and Harriet Martineau. With footings established in spite of constant persecution, the Unitarian religion began to assume organizational form. Journals, schools, and new churches appeared wherever the fierce objections of orthodox authorities could be overcome. In Poland, orthodox reaction was violent enough to exterminate the strong liberal movement.

Early in the eighteenth century, liberal thought began to find expression in American pulpits. During the last half of the eighteenth century, a few isolated religious leaders in England and America began to preach the doctrine that it was unthinkable for a loving God to damn any person everlastingly to hell.

In the 1740s these heretical notions were preached in Pennsylvania by Universalist Dr. George de Benneville. In the 1760s similar ideas brought about the excommunication from Methodism of John Murray. These Universalists proclaimed the final harmony of the human soul with God. John and Judith Murray in 1770 helped to found the Universalist Church in America.

The Calvinist majority in the northern colonies was disturbed by this wandering from “sound” doctrine. There was immediate denunciation of the Universalists as an irresponsible lot bent on encouraging a life of reckless wickedness, counting on escaping the tortures of hell. Standing against the orthodox majority, Universalists stressed the ethical nature of God.

In 1800 a man of outstanding preaching ability appeared on the New England scene, a courageous, persuasive, and scholarly Universalist preacher named Hosea Ballou. In 1803 the Universalists adopted the Winchester Profession, which became the standard expression of Universalist views, emphasizing God’s universal love and the example and leadership of Jesus, and coined the phrase “salvation by character.”

The first churches in America to assume the Unitarian name were founded by Dr. Joseph Priestley in Northumberland, Pennsylvania (1794) and in Philadelphia (1796). Though known as the discoverer of oxygen and one of the most celebrated of English scientists, Dr. Priestley was by profession a Unitarian minister.

After orthodox fanatics burned his laboratory in Birmingham, England, Priestley came to the American colonies to seek a religious atmosphere less contaminated by orthodox bigotry. His arrival in America was a catalyst. Intellectual and moral revolt against orthodox doctrines was sweeping across the eastern seaboard. Churches of many denominations were caught up in the desire to re-examine their theological beliefs and backgrounds. Boston’s historic King’s Chapel, the first Episcopal church in New England, led the way in 1785. The congregation called a minister of Unitarian persuasion and revised its book of common prayer to eliminate Trinitarian references.

In 1802 the oldest Pilgrim church, founded at Plymouth in 1620, became Unitarian by congregational vote. This pattern was repeated in more than 100 cities and towns. Meanwhile there had emerged in Boston a Unitarian leader of eloquence and force of personality, Dr. William Ellery Channing, under whose inspiration the American Unitarian Association was founded on May 25, 1825. By coincidence, the British Unitarian Association was officially organized on the same day. In each country the scattered, independent liberal congregations pooled their strengths in a formal, cooperative way, and their futures were assured.

In the early days there was little enthusiasm for close ties between the Unitarians and the Universalists. This pained Ballou, who wrote eloquently of the affinity of the two groups, recalling their common aspirations and frustrations, and calling for intellectual and spiritual unity. During the 20th century the two groups grew increasingly aware of one another, and passed more than a dozen resolutions calling for union. Finally in 1947, a joint commission was established to lay the groundwork for Federal Union, and by 1951 it presented a recommendation for immediate union in the fields of religious education, publications, and public relations, with a gradual trend toward complete merger, which was effected in Boston in May 1960. Total consolidation was completed in May 1961.

About the Author
Rev Dr. Jack Mendelsohn (1918-2012) served for many years as minister of historic Arlington Street Church in Boston when the church was prominent for its antiwar and civil rights work. Later he became minister of the First Unitarian Church of Chicago where he also served on the faculty of Meadville/Lombard Theological School. The Unitarian Universalist Association honored him with its Distinguished Service Award in 1997.