Robert Treat Paine was a Congregationalist and a devout Christian. He worked as a full-time Congregationalist clergyman, among other occupations, prior to signing the Declaration of Independence. Later he left Congregationalism and Calvinism and embraced Unitarianism, which during that era was an alternative denomination within Protestant Christianity.
He was identified as a Congregationalist by The Congregationalist Library. (Source: Ian Dorion, "Table of the Religious Affiliations of American Founders", 1997).
From: B. J. Lossing, Signers of the Declaration of Independence, George F. Cooledge & Brother: New York (1848) [reprinted in Lives of the Signers of the Declaration of Independence, WallBuilder Press: Aledo, Texas (1995)], pages 37-38:
This distinguished patriot was born in Boston, Massachusetts, in 1731. His father was a clergyman, and his mother was the daughter of the Reverend Mr. Treat, of Barnstable county. His maternal grandfather was Governor Treat, of Connecticut...From: Robert G. Ferris (editor), Signers of the Declaration: Historic Places Commemorating the Signing of the Declaration of Independence, published by the United States Department of the Interior, National Park Service: Washington, D.C. (revised edition 1975), page 115-116:
Young Paine entered Harvard College at the age of fourteen years, and graduated with the usual honors. For a time after leaving college he taught school. He then made a voyage to Europe, and on his return he prepared himself for the ministry, in which calling he was engaged as chaplain in a military expedition to the north in 1755. Not long afterward he relinquished theology, studied law with Mr. Pratt, (afterward Chief Justice of New York,) and was admitted to practice at the bar.
A clergyman turned lawyer-jurist, Robert Treat Paine spent only a short time in Congress but enjoyed considerable political prestige in Massachusetts. His second son (1773-1811) and great-grandson (1835-1910), both bearing exactly the same names as he, gained fame respectively as poet and businessman-philanthropist.From: Rev. Charles A. Goodrich, Lives of the Signers to the Declaration of Independence, New York: William Reed & Co. (1856), pages 112-119 (http://www.colonialhall.com/painert/painert.php; viewed 28 November 2005):
Among the ancestors of Paine, who was born at Boston in 1731, were many New England religious and political leaders. His father was a merchant who had once been a clergyman. Young Paine led his class at Boston Latin School and graduated from Harvard in 1749. He then taught school for a time before yielding to family tradition and entering the ministry.
In 1755, during the French and Indian war, he served as chaplain on a military expedition to Crown Point, N.Y. To improve his health, he made a voyage to the Carolinas, England, Spain, and Greenland.
Paine, a friend of John Adams and John Hancock, early became involved in the patriot movement. As a result, he was chosen in 1770 as one of the prosecuting attorneys in the Boston Massacre trial and thus gained recognition throughout the Colonies. That same year, he married, siring eight children. Between 1773 and 1778, except in 1776, he served in the Massachusetts legislature, in 1777 being speaker of the lower house. He was one of the first five Delegates sent by Massachusetts to the Continental Congress (1774-76), where he specialized in military and Indian affairs. He gained the nickname "Objection Maker" because he argued against so many proposals.
Although reelected to Congress in 1777, Paine chose to stay in Massachusetts. In addition to his legislative speakership, he was elected as the first attorney general, a position he held until 1790. Between 1778 and 1780 he played a prominent role in drafting the Massachusetts constitution. From 1790 until 1804, appointed by his old friend Hancock, he sat as an associate justice of the Superior Court.
Meantime, in 1780, Paine had moved from Taunton to Boston and become active in civic affairs. Indicative of his lifelong interest in science, that same year he was one of the founders of the American Academy of Arts and Sciences. In religion, he broke away from Calvinism and embraced Unitarianism. Politically, he alined himself with the Federalists. In 1804 increasing deafness brought about his retirement from the Superior Court, and he died a decade later at the age of 83 in Boston. He was buried in the Old Granary Burying Ground.
Robert Treat Paine was a native of Boston, where he was born, in the year 1731. His parents were pious and respectable. His father was for some years the settled pastor of a church in Weymouth, in the vicinity of Boston. His health failing him, however, he removed with his family to the latter place; where he entered into mercantile pursuits. His mother was the grand-daughter of Governor Treat of Connecticut...
Previously to his commencing the study of laws he devoted some time to the subject of theology, which tended to enlarge his views of Christianity, and to confirm his belief of its truth. In 1755, he served as chaplain to the troops of the province at the northward, and afterwards preached a few times in other places...
Few men have rendered more important services to the literary and religious institutions of a country, than did Judge Paine. He gave them all the support and influence of his office, by urging upon grand jurors the faithful execution of the laws, the support of schools, and the preservation of strict morality...
As a scholar, he ranked high among literary men, and was distinguished for his patronage of all the useful institutions of the country. He was a founder of the American Academy established in Massachusetts in 1780, and active in its service until his death. The honorary degree of doctor of laws was conferred upon him by Harvard University.
Judge Paine was a firm believer in the divine origin of the Christian religion. He gave full credence to the scriptures, as a revelation from God, designed to instruct mankind in a knowledge of their duty, and to guide them in the way to eternal happiness.