Ridicule is the only weapon which can be used against unintelligible propositions. Ideas must be distinct before reason can act upon them; and no man ever had a distinct idea of the trinity. It is the mere Abracadabra of the mountebanks calling themselves the priests of Jesus. If it could be understood it would not answer their purpose. Their security is in their faculty of shedding darkness, like the scuttle fish, thro’ the element in which they move, and making it impenetrable to the eye of a pursuing enemy. And there they will skulk, until some rational creed can occupy the void which the obliteration of their duperies would leave in the minds of our honest and unsuspecting brethren.

Thomas Jefferson, letter to Francis van der Kemp, August 6, 1816

In the present weak State of humane Nature, surrounded as we are on all sides with Ignorance and Error, it little becomes poor fallible Man to be positive and dogmatical in his Opinions. No Point of Faith is so plain, as that Morality is our Duty, for all Sides agree in that. A virtuous Heretick shall be saved before a wicked Christian.

Benjamin Franklin, Dialogue Between Two Presbyterians, April 10, 1735

Calvinism has introduced into the Christian religion more new absurdities than it’s leader had purged it of old ones.

Thomas Jefferson, letter to Salma Hale, July 26, 1818

Yes, I saw the apostrophe. It’s original.

That there is such a Person as The Devil is no part of my Faith, nor that of many other Christians; nor am I sure that it was the belief of any of the christian Writers. Neither do I believe the doctrine of demoniacal possessions, whether it was believed by the sacred Writers or not; and yet my unbelief in these Articles does not affect my faith in the great facts of which the Evangelists were eye and ear witnesses.

John Adams, letter to Thomas Jefferson, March 3, 1814

It has been by wandering from the immutable laws of science, and the light of reason, and setting up an invented thing, called revealed religion, that so many wild and blasphemous conceits have been formed of the Almighty.

Thomas Paine, The Age of Reason Part Two, 1795

The Church of Rome has made it an Article of Faith that no man can be saved out of their Church, and all other religious Sects approach to this dreadfull opinion in proportion to their Ignorance, and the Influence of ignorant or wicked Priests.

John Adams, from his diary, February 16, 1756

I do not believe that any two men, on what are called doctrinal points, think alike who think at all. It is only those who have not thought that appear to agree.

Thomas Paine, The Rights of Man Part Two, 1792

I expect our principle contributions [for building a black church] will come from the Deists, swearing captains of vessels, and brokers of our city. The clergy and their faithful followers of every denomination are too good to do good.

Benjamin Rush, letter to Julia Rush, July 16, 1791

There is in human Nature a solid, unchangeable and eternal Foundation of Religion. There is also a germ of superstition, seemingly a fungous growth or a spurious sprout, which the grossest Blockheads and most atrocious Villains are able to cultivate into Systems and Sects to deceive millions and cheat and pillage hundreds and thousands of their fellow Creatures.

John Adams, letter to John Quincy Adams, May 10, 1816

That humans have an innate tendency to believe in a religion is something I can believe. I just personally think it’s part of the superstition, which is much more than a germ.

Christianity is an active, affectionate and social religion, chiefly consisting in a discharge of duties to our fellow creatures. It therefore requires no separation from them. Tho enjoining that we “be not conformed to the world,” in following this direction, the utmost attention is necessary lest distinctions from others by plainness of manners and customs assume the place of virtues, and become snares. Such distinctions are not in the least value in themselves because they are no part of the Divine Laws.

John Dickinson, Religious Instruction for Youth

Dickinson was a noted pamphleteer and defender of the Constitution. I do not have a date for this.