If we demand that politicians be honest and open about their religious beliefs, then Thomas Jefferson would not be the only casualty.
Abraham Lincoln could not have been elected either.
This
webpage takes a a very detailed look at Lincoln's religious beliefs.
Some very interesting excerpts:
The last witness quoted by Colonel Lamon is Mrs.
Mary Todd Lincoln, wife of the martyred President. She says of her husband's religious views: "Mr. Lincoln had no hope, and no faith, in the usual acceptation of those words." (Life of Lincoln, p. 459.) She also made the following statement to Mr. Herndon: "Mr. Lincoln's maxim and philosophy were: 'What is to be, will be, and no prayers of ours can arrest the decree.' He never joined any Church. He was a religious man always, I think, but was not a technical Christian." (Herndon, Religion of Lincoln.)
(snip)
"Mr. Lincoln was never a member of any Church, nor did he believe in the divinity of Christ, or the inspiration of the Scriptures in the sense understood by evangelical Christians." (Life of Lincoln, p. 486.)
(snip)
"The community in which he lived was preeminently a community of Freethinkers in matters of religion; and it was no secret, nor has it been a secret since, that Mr. Lincoln agreed with the majority of his associates in denying the authority of divine revelation. It was his honest belief, a belief which it was no reproach to hold in New Salem, Anne Domino, 1834, and one which he never thought of concealing. It was no distinction, either good or bad, no honor, and no shame. But he had made himself thoroughly familiar with the writings of Paine and Volney -- the Ruins by the one, and The Age of Reason by the other. His mind was full of the subject, and he felt an itching to write. He did write, and the result was a little book. It was probably merely an extended essay, but it is ambitiously spoken of as 'a book' by himself and by the persons who were made acquainted with its contents. In this work he intended to demonstrate --
"'First, that the Bible is not God's revelation.
"'Second, that Jesus was not the son of God.'
"No leaf of this volume has survived. Mr. Lincoln carried it in manuscript to the store of Samuel Hill, where it was read and discussed. Hill was himself an unbeliever, but his son considered his book 'infamous.' It is more than probable that Hill, being a warm personal friend of Lincoln, feared that the publication of the essay would some day interfere with the political advancement of his favorite. At all events, he snatched it out of his hand, and threw it into the fire, from which not a shred escaped." (Ibid, pp. 157, 158.)
"As he grew older, he grew more cautious; and as his New Salem associates, and the aggressive Deists with whom he originally united at Springfield, gradually dispersed, or fell away from his side, he appreciated more and more keenly the violence and extent of the religious prejudice which freedom in discussion from his standpoint would be sure to arouse against him. He saw the immense and augmenting power of the Churches, and in times, past had practically felt it. The imputation of Infidelity had seriously injured him in several of his earlier political contests; and, sobered by age and experience, he was resolved that the same imputation should injure him no more. Aspiring to lead religious communities, he foresaw that he must not appear as an enemy within their gates; aspiring to public honors under the auspices of a political party which persistently summoned religious people to assist in the extirpation of that which it denounced as the 'nation's sin,' he foresaw that he could not ask their suffrages whilst aspersing their faith. He perceived no reason for changing his convictions, but he did perceive many good and cogent reasons for not making them public." (Ibid, pp. 497, 498.)
(snip)
The next witness quoted by Colonel Lamon was Colonel James H. Matheny, who was not only a friend of Lincoln, but for a while his political manager. He said:
"I knew Lincoln as early as 1834-7; knew he was an Infidel. He and W. D. Herndon used to talk Infidelity in the Clerk's office in this city, about the years 1837-40. Lincoln attacked the Bible and the New Testament on two grounds: first, from the inherent or apparent contradictions under its lids; second, from the grounds of reason. Sometimes he ridiculed the Bible and the New Testament, sometimes seemed to scoff at it, though I shall not use that word in it's full and literal sense. I never heard that Lincoln changed his views, though his personal and political friend from 1834 to 1860. Sometimes Lincoln bordered on Atheism. He went far that way and shocked me. I was then a young man, and believed what my good mother taught me. Stuart and Lincoln's law office was in what is called Hoffman's Row, on North Fifth Street, near the public square. It was in the same building as the Clerk's office, and on the same floor. Lincoln would come into the Clerk's office, where I and some young men -- Evan Butler, Newton Francis and others -- were writing or staying, and would bring the Bible with him; would read a chapter, argue against it. Lincoln then had a smattering of geology, if I recollect it. Lincoln often, if not wholly, was an Atheist; at least bordered on it. Lincoln was enthusiastic in his Infidelity. As he grew older he grew more discreet, didn't talk much before strangers about his religion; but to friends, close and bosom ones, he was always open and avowed, fair and honest; but to strangers, he held them off from policy. Lincoln used to quote Burns. Burns helped Lincoln to be an Infidel, as I think; at least he found in Burns a like thinker and feeler.