The Presbyterian clergy are the loudest, the most intolerant of all sects; the most tyrannical and ambitious, ready at the word of the lawgiver, if such a word could now be obtained, to put their torch to the pile, and to rekindle in this virgin hemisphere the flame in which their oracle, Calvin, consumed the poor Servetus, because he could not subscribe to the proposition of Calvin, that magistrates have a right to exterminate all heretics to the Calvinistic creed! They pant to re-establish by law that holy inquisition which they can now only infuse into public opinion.
-- Thomas Jefferson to William Short, April 13, 1820
One reason I think the famous sermon given by a Rev. Wil[l]son in 1831 terming all of our Presidents from Washington to Jackson "unitarians" and "infidels," and thundering that God was voted out of the Constitution was probably given by the Presbyterian James Remnick Willson and not the Episcopalian Bird Wilson is because of its harsh and biting tone. Sure there were Episcopalians who could be judgmental and a few of them threw around the "i" word (infidel); such was far more characteristic, however, of Calvinist/Presbyterians. Indeed, it was a Presbyterian denomination, after all, which, like Patrick Henry, "smelt a rat," refused to accept the US Constitution. (Though, Henry, an Episcopalian, was probably more concerned with the federal government having too much power; these Presbyterians, from what I've been able to glean, would have had no problem with a more powerful central government so long as it imposed a religious test and covenanted with the Triune God of the Bible). And the Revered Willson was a member of that Presbyterian Church.
In his sermons, the Reverend Willson "judges" George Washington as not a real Christian. In his most notorious one, he stated:
There is no satisfactory evidence that Washington was a professor of the Christian religion, or even a speculative believer in its divinity, before he retired from public life. In no state paper, in no private letter, in no conversation, is he known to have declared himself a believer in the Holy Scriptures, as the word of God.
Some orthodox "non-Presbyterian" ministers also thought Washington wasn't Christian. Most notable is the Rev. James Abercrombie, Washington's own minister in Philadelphia who reprimanded Washington for refusing to take communion. But most orthodox Christian ministers of the founding era, perhaps wishful thinking, probably thought Washington was a real Christian. Even Bishop White, who gave key testimony that Washington didn't commune (and Rev. Abercrombie's boss), refused to "judge" Washington as a "Deist" and basically said he didn't know what to make of it; though he didn't have evidence of any smoking gun statements which would prove Washington a believer in Christianity. His exact words:
"I do not believe that any degree of recollection will bring to my mind any fact which would prove General Washington to have been a believer in the Christian revelation further than as may be hoped from his constant attendance upon Christian worship, in connection with the general reserve of his character."
Peter A. Lillback exaggerates and claims that practically all of the orthodox Christian ministers of the Founding era thought Washington was a real Christian. More realistically, perhaps a majority of orthodox Christian ministers thought Washington a real Christian; though many had their doubts. Some corresponded with Washington to try and "feel him out." And yes, the ministers most likely to doubt Washington's belief in real Christianity were...the Presbyterians.
This should help explain the context behind Jefferson's famous lines doubting Washington's belief in Christianity:
Dr. Rush tells me that he had it from Asa Green that when the clergy addressed Genl. Washington on his departure from the govmt, it was observed in their consultation that he had never on any occasion said a word to the public which showed a belief in the Xn religion and they thot they should so pen their address as to force him at length to declare publicly whether he was a Christian or not. They did so. However he observed the old fox was too cunning for them. He answered every article of their address particularly except that, which he passed over without notice. Rush observes he never did say a word on the subject in any of his public papers except in his valedictory letter to the Governors of the states when he resigned his commission in the army, wherein he speaks of the benign influence of the Christian religion.
I know that Gouverneur Morris, who pretended to be in his secrets & believed himself to be so, has often told me that Genl. Washington believed no more of that system than he himself did.
"Asa Green" was the Rev. Ashbel Green, the President of Princeton after John Witherspoon, a Congressional Chaplain, and frequent dinner quest of and correspondent with George Washington. So he knew Washington well. Ashbel Green led a group of Presbyterian Clergy who tried to pin Washington down to put his religious cards on the table. The "cunning old fox" wouldn't play ball. And that led them to judge him as a "deist" or not "real Christian." Rev. Willson also discussed the incident:
When the several classes of citizens, were addressing Washington, on his retirement from office, the clergy, who doubted his Christianity, resolved to frame an address, so that he could not evade, in his reply, an expression of his faith, if he were really a believer. He did, however, evade it, and the impression left on the mind of one of the clergy, at least, was that he was a Deist.
And the following from a letter from Hon. A.B. Bradford, a prominent clergyman in the Presbyterian church, confirms what Jefferson and Willson stated:
"I knew Dr. Wilson personally, and have entertained him at my house, on which occasion he said in my hearing what my relative, the Rev. Dr. Ashbel Green of Philadelphia, frequently told me in his study, viz., that during the time that Congress sat in that city the clergy, suspecting from good evidence that Washington was not a believer in the Bible as a revelation from heaven, laid a plan to extort from him a confession, either pro or con, but that the plan failed. Dr. Green was chaplain to Congress during all the time of its sitting in Philadelphia; dined with the President on special invitation nearly every week; was well acquainted with him, and after he had been dead and gone many years, often said in my hearing, though very sorrowfully, of course, that while Washington was very deferential to religion and its ceremonies, like nearly all the founders of the Republic, he was not a Christian, but a Deist."
In a Chicago Tribune article by B.F. Underwood, Bradford was also quoted as follows:
"It was during his [Dr. Green's] long residence in Philadelphia that I became intimately acquainted with him as a relative, student of theology at Princeton, and a member of the same Presbytery to which he belonged. Many an hour during my student and clergyman days did I spend with him in his study at No. 150 Pine street, Philadelphia, listening to his interesting and instructive conversation on Revolutionary times and incidents. I recollect well that during one of these interviews in his study I inquired of him what were the real opinions Washington entertained on the subject of religion. He promptly answered pretty nearly in the language which Jefferson says Dr. Rush used. He explained more at length the plan laid by the clergy of Philadelphia at the close of Washington's administration as President to get his views of religion for the sake of the good influence they supposed they would have in counteracting the Infidelity of Paine and the rest of the Revolutionary patriots, military and civil. But I well remember the smile on his face and the twinkle of his black eye when he said: 'The old fox was too cunning for Us.' He affirmed, in concluding his narrative, that from his long and intimate acquaintance with Washington he knew it to be the case that while he respectfully conformed to the religious customs of society by generally going to church on Sundays, he had no belief at all in the divine origin of the Bible, or the Jewish-Christian religion."
Now, these ministers may not have been right, or perhaps overstated their claim (I for one think that Washington probably believed at least some of the Bible was divinely inspired; though, like Jefferson, Franklin and the others, he probably didn't believe the whole thing was). But this shows at the very least that prominent Presbyterians, some who, like Ashbel Green knew him quite well, doubted Washington's belief in orthodox Christianity.
Finally, some orthodox Christians thought Washington's death reason to doubt his Christianity. His death was entirely stoic. He asked for no ministers and said no prayers. His final words were "tis well." The Rev. Samuel Miller, a founding era figure, thus commented: "How was it possible...for a true Christian, in the full exercise of his mental faculties, to die without one expression of distinctive belief, or Christian hope?"
And yes, Rev. Miller was...a Presbyterian. (Though, Miller wasn't all that bad. He was one of the few prominent Presbyterians to endorse Jefferson's Presidency.)