Unitarianism is the belief that God exists in one person, not three. It is a denial of the doctrine of the Trinity as well as the full divinity of Jesus. There are several groups that fall under this umbrella: Jehovah’s Witnesses, Christadelphianism, The Way International, etc. Unitarian Universalists use many biblical concepts and terms but with non-biblical meanings.
Unitarians have always held that Jesus Christ was a man, and though he undoubtedly was exceptional, he was not the God-made-man of most Christian belief. Unitarians believe that it is of utmost importance to try to lead a moral life based on Christian principles. They do not, however, adhere to the Fundamentalists’ views on the infallibility of the Bible.
While there were previous antitrinitarian movements in the early Christian Church, like Arianism and Monarchianism, modern Unitarianism originated in the period of the Protestant Reformation.
In the mid-1800s, Unitarianism became a religion of reason under the leadership of James Martineau in England and Ralph Waldo Emerson and Theodore Parker in the United States. Reason and conscience were considered the only guides to religious truth; complete religious tolerance, innate human goodness, and universal salvation were preached.
Unitarians believe that religious authority does not lie within a book or institution but within people. They do not believe anyone should ascribe to a creed, and say theirs is a non-creedal religion. They espouse that religious wisdom is ever-changing and that personal experience, conscious, and reason should be the final authority in religion.
Often allied to the Unitarians (especially in the United States) are the Universalists. They are similar in their approach to religion, although the basis of Universalism is the notion that all human beings are loved by God, and that therefore they could all get to heaven, even if they had never heard of Christianity.
Today, Unitarian/Universalist churches number almost 300,000 worldwide, with most members living in Great Britain, the United States, Canada, and Eastern Europe. Although membership is slowly growing, only about 1 in every 1300 Americans claim Unitarian/Universalist membership.