On November 4, 1820, Thomas Jefferson wrote a letter to the Reverend Jared Sparks. He stated:

"I hold the precepts of Jesus, as delivered by Himself, to be the most pure, benevolent, and sublime which have ever been preached to man.  I adhere to the principles of the first age; and consider all subsequent innovations as corruptions of His religion, having no foundation in what came from Him. The metaphysical insanities of Athanasius, of Loyola, and of Calvin, are, to my understanding, mere relapses into polytheism, differing from paganism only by being more unintelligible.  The religion of Jesus is founded in the Unity of God, and this principle chiefly, gave it triumph over the rabble of heathen gods then acknowledged.  Thinking men of all nations rallied readily to the doctrine of one only God, and embraced it with the pure morals which Jesus inculcated.  If the freedom of religion, guaranteed to us by law in theory, can ever rise in practice under the overbearing inquisition of public opinion, truth will prevail over fanaticism, and the genuine doctrines of Jesus, so long perverted by His pseudo-priests, will again be restored to their original purity.  This reformation will advance with the other improvements of the human mind, but too late for me to witness it.”

(The Writings of Thomas Jefferson V15: Containing His Autobiography, Notes on Virginia, Parliamentary Manual, Official Papers, Messages and Addresses, And Other Writings And Private (Lipscomb and Bergh, Eds.; Kessinger Publishing, 2006), 15:288 (emphasis in original))

One other quotation from Thomas Jefferson on apostasy and restoration:

"Happy in the prospect of a restoration of primitive Christianity, I must leave to younger athletes to encounter and lop off the false branches which have been engrafted into it by the mythologists of the middle and modern ages."

(Letter to Dr. Benjamin waterhouse, in The Writings of Thomas Jefferson V15: Containing His Autobiography, Notes on Virginia, Parliamentary Manual, Official Papers, Messages and Addresses, and Other Writings and Private (Lipscomb and Bergh, Eds., Kessinger Publishing, 2006), 15:391)

Thomas Jefferson seemed to believe he was alone in his feelings on Christ’s church:

"You say you are a Calvinist. I am not. I am of a sect by myself, as far as I know."

(Letter to Ezra Stiles Ely, 6/25/1819)