The Unitarian Church... But the movement goes back at least to Michel Servet who was burned at the stake by Calvin!
From http://www.uua.org/aboutuu/uufaq.html#who
"In the sixteenth century, Christian humanists in Central Europe-in Poland and Transylvania-studied the Bible closely. They could not find the orthodox dogma of the Trinity in the texts. Therefore, they affirmed-as did Jesus, according to the Gospels-the unity, or oneness, of God. Hence they acquired the name Unitarian.
These sixteenth-century Unitarians preached and organized churches according to their own rational convictions in the face of overwhelming orthodox opposition and persecution. They also advocated religious freedom for others. In Transylvania, now part of Romania, Unitarians persuaded the Diet (legislature) to pass the Edict of Toleration. In 1568 the law declared that, since "faith is the gift of God," people would not be forced to adhere to a faith they did not choose.
In the seventeenth and eighteenth centuries, radical reformers in Europe and America also studied the Bible closely. They found only a few references to hell, which they believed orthodox Christians had grossly misinterpreted. They found, both in the Bible and in their own hearts, an unconditionally loving God. They believed that God would not deem any human being unworthy of divine love, and that salvation was for all. Because of this emphasis on universal salvation, they called themselves Universalists...."
It does not, in any way, show that Adams was a "Unitarian", especially given the current definition. I suspect you have fabricated this bit of information.