Unitarian Universalism emerged from two different religions: Unitarianism and Universalism. Both Unitarianism and Universalism started in Europe hundreds of years ago. The Universalist Church of America (UCA) was founded by 1793, and the American Unitarian Association (AUA) by 1825. In 1961, these denominations consolidated to form the new denomination of Unitarian Universalism.
Originally, all Unitarians were Christians who didn't believe in the Holy Trinity of God (Father, Son, and Holy Ghost). Instead, they believed in the unity, or single aspect, of God. Unitarianism eventually began to stress the importance of rational thinking, each person's direct relationship with God, and the humanity of Jesus.
Unitarians have been very influential throughout American history, especially in politics and literature. Some famous Unitarians include Presidents John Adams and John Quincy Adams, Louisa May Alcott, Ralph Waldo Emerson, Paul Revere, President William Howard Taft, and Frank Lloyd Wright.
While Unitarian beliefs have been around since soon after Jesus died, people didn't form religious groups based on the ideas until the middle of the fifteen hundreds in Transylvania and the middle of the sixteen hundreds in England. The religious authorities of the times saw these early Unitarians as heretics and often persecuted them. Important figures from this period in Unitarian history include John Biddle, Francis David, Michael Servetus, King John Sigismund and Faustus Socinus.
Unitarianism flourished in the religious freedom of early America. By 1825 Unitarian ministers had formed a Unitarian denomination called the American Unitarian Association. Speaking out on issues such as peace, education reform, prison reform, orphanages, capital punishment, moderation in temperance, ministry to the poor, and the abolition of slavery, the AUA's liberal voice was soon heard throughout the country. The influential Unitarians from this era included William Ellery Channing, Theodore Parker, Joseph Priestly, and Thomas Starr King, who was also a Universalist.
American Unitarianism went through many changes over the next 150 years, from the introduction of Transcendentalist thought in the middle of the eighteen hundreds through debates about war and pacifism in the Civil War and the two World Wars to the influx of Humanism in the early 1930s. These changes slowly made Unitarianism a more broad and flexible faith.
There are many Unitarian congregations today outside the United States that are part of the Unitarian Universalist community. The largest concentrations of Unitarians outside the United States are in Transylvania (now part of Romania and Hungary) and India. There are also Unitarian organizations that are not affiliated with Unitarian Universalism, most of which call themselves Biblical or Christian Unitarians. You can search the internet to find more information on these groups.
Originally, Universalists were Christians who believed in universal salvation. They didn't believe that a loving God could punish anyone to hell for eternity. Instead, they believed that everyone would be reconciled with God eventually.
Universalists have been influential throughout American history. Some famous Universalists include Clara Barton, Olympia Brown, Thomas Starr King, Horace Greeley, George Pullman, Mary Livermore, and Benjamin Rush.
While Universalist beliefs have been proclaimed for thousands of years, starting with Origen in 200 CE and continuing through to James Relly in the sixteen hundreds, the faith didn't have the opportunity to form into a widespread religious movement until English Universalists came to America in the late 1700s to escape religious persecution.
Because of its loving and inclusive doctrine, Universalism quickly became popular throughout the United States, especially in rural areas and the expanding western states. The Universalist denomination, called the Universalist Church of America, was formed by 1793. Universalists including Hosea Ballou, John Murray, and Benjamin Rush helped to spread and develop their faith's teachings throughout the denomination's early years.
Universalists were best known for supporting education and non-sectarian schools, but they also worked on social issues including the separation of church and state, prison reform, capital punishment, the abolition of slavery, and women's rights. In 1863 the Universalists became the first group in the United States to ordain a woman with full denominational authority.
The Civil War unfortunately destroyed many Universalist churches and killed many Universalist ministers who had served as chaplains for the armies. Soon after, a softer approach to the idea of damnation became popular throughout the US in the mid to late eighteen hundreds, making the Universalist denomination less unique in its teachings. The denomination struggled for many years as membership waned.
There are some Universalist congregations today outside the US that consider themselves to be part of the Unitarian Universalist community. The largest concentration of Universalists outside the US is in the Philippines. There are also Universalist organizations that are not affiliated with Unitarian Universalism, most of which call themselves Christian Universalists.
After growing increasingly theologically and ethically close, the Universalist and Unitarian denominations consolidated in 1961 to form the new religion of Unitarian Universalism. Unitarian Universalism no longer solely holds traditional Universalist or Unitarian beliefs, but does draw directly on its heritage for much of its inspiration and grounding.