Livingston moved from New York to New Jersey in 1770. From then on, he was an active member of the Presbyterian Church, the most Orthodox sect in Christianity. However in 1753, his writings could appear less Orthodox than later in life. His disdain for Creeds targeted the Clergy, not the Scriptures:
"[T]he Use of Creeds, which is the construction of the Clergy upon the Scriptures." p. 390Moreover, by 1770, Livingston was an active Presbyterian. His Presbyterian daughter, Sarah married John Jay April 28, 1774, and he could never have been a trustee of Princeton if he walked out of Communion; as George Washington did.
In recognition of his prominence in Presbyterian circles, he had been appointed a trustee of the College of New Jersey (Princeton) in 1768, and the student newspaper had been named the "American Whig" in his honor. In 1771 he had been a founding member of the "New Jersey Society for the better Support of the Widows and Education of the Children of deceased Presbyterian Ministers...--Introduction, The Papers of William Livingston. Vol 1, June 1774-77. Carl E. Prince, Editor, New Jersey Historical Commission, Trenton. 1979. p. 7.
His serious involvement with the Presbyterians is evidenced in this note to his son:
With respect to your entring a Sophomore & then staying another year at Elizabeth Town under Mr. Periam..I think it best for us to take the opinion of Dr. Witherspoon on that subject.--To William Livingston Jr. March 1, 1777. Papers of Livingston, p. 262.
Mr. Livingston was trusting Witherspoon with his son's education. I doubt Witherspoon or the other trustees, would have allowed Livingston into their hierarchy if he walked out of communion. Here is the charter. Maybe someone can decipher it.