"I have examined all the known superstitions of the word, and I do not find in our particular superstition of Christianity one redeeming feature. They are all alike founded on fables and mythology. Millions of innocent men, women and children, since the introduction of Christianity, have been burnt, tortured, fined and imprisoned. What has been the effect of this coercion? To make one half the world fools and the other half hypocrites; to support roguery and error all over the earth."
--Thomas Jefferson, letter to William Short
"The truth is that the greatest enemies to the doctrines of Jesus are those calling themselves the expositors of them, who have perverted them for the structure of a system of fancy absolutely incomprehensible, and without any foundation in his genuine words."
Many other of the Founders and leaders of our country have evidenced similar sentiments, yet still felt that they were "Christians" because they held to the underlying beliefs of "correct morality" and "loving benevolence", and eschewed the orthodoxy and piousness of the "clergy" and their proponents.
"I concur with you strictly in your opinion of the comparative merits of atheism and demonism, and really see nothing but the latter in the being worshipped by many who think themselves Christians."
--Thomas Jefferson, letter to Richard Price, 1789
Jefferson himself did not disparage the teachings of Jesus, just those who had perverted them.
"Christianity...(has become) the most perverted system that ever shone on man. ...Rogueries, absurdities and untruths were perpetrated upon the teachings of Jesus by a large band of dupes and importers led by Paul, the first great corrupter of the teaching of Jesus."
--Thomas Jefferson, letter to William Short, 1820
As said, others of the time seemed to share Jefferson's opinion of Christianity:
"The divinity of Jesus is made a convenient cover for absurdity. Nowhere in the Gospels do we find a precept for Creeds, Confessions, Oaths, Doctrines, and whole carloads of other foolish trumpery that we find in Christianity."
"The study of theology, as it stands in the Christian churches, is the study of nothing; it is founded on nothing; it rests on no principles; it proceeds by no authority; it has no data; it can demonstrate nothing; and it admits of no conclusion."
Apparently ol' Tom had some of your ilk in mind when he said:
"The Bible is a book that has been read more and examined less than any book that ever existed."
Evidently Ben Franklin shared some of the distaste for the orthodoxy - not the scriptures- when he wrote to his father in 1738: "I think vital religion has always suffered when orthodoxy is more regarded than virtue. The scriptures assure me that at the last day we shall not be examined on what we thought but what we did."
And then again when he observed: "Lighthouses are more helpful than churches."
Mr Lincoln got into the same train of thought when he wrote: "The Bible is not my book, and Christianity is not my religion. I could never give assent to the long, complicated statements of Christian dogma." Again, I think he was talking more about the orthodoxy and structure of the church at that time rather than the underlying principles of Jesus.
"My husband is not a Christian but is a religious man, I think."
--Mary Todd Lincoln
But again, I am reminded of the old saying about teaching pigs to dance. As old Ben so aptly put it:
"Indeed, when religious people quarrel about religion, or hungry people quarrel about victuals, it looks as if they had not much of either among them."
I don't know why you have such a problem understanding that.
Protestants churches all disagree with each other. All of them think they are right, and all the other churches are wrong. All of them think they have the correct interpretation of scripture.
It may serve your militant atheist agenda to cast doubt on the piety of this nation's Founders, but the fact that they dismissed Christian religious practices which conflicted with their own dogmas only shows the strength of their religious persuasion and their desire to practice "true Christianity."