Unitarian emphasis on the exercise of human reason caused Unitarians to cease to regard the Bible as the ultimate authority in matters of faith.  In the 19th century the Universalist church was the first to ordain women. The American Unitarian Association was organized in Boston in May of 1825 and met annually in Boston until the merger with the Universalist Church of America in 1961. 
 

In sixteenth century Transylvania, Francis David (1510-1579) became the founder of the first Unitarian faith to be known literally as Unitarian. Francis David had originally trained as a Catholic priest before becoming a Lutheran and then a Calvinist, and then finally a Unitarian. In the year 1568, King John Sigismund called a Diet (debate) in the city of Turda to determine which of the established religions in the area would be declared the official religion of his realm. During that lengthy debate, Francis David held his ground against all the other established religions in the region and convinced King John Sigismund that to declare one religion as the state religion and to compel his people to follow that religion was wrong. King John proclaimed religious freedom throughout his realm, the first such declaration known in history.  This victory did not last long, within three years King John was dead, and his successor did not hold his tolerant views.  Francis David was ultimately sentenced to prison for refusing to acknowledge that Jesus Christ was to be at least Adored, and he died in the prison at Deva in 1579.