MONTICELLO, December 8, 1822. SIR,--I have to thank you for your pamphlets on the subject of Unitarianism, and to express my gratification with your efforts for the revival of primitive Christianity in your quarter. No historical fact is better established, than that the doctrine of one God, pure and uncompounded, was that of the early ages of Christianity; and was among the efficacious doctrines which gave it triumph over the polytheism of the ancients, sickened with the absurdities of their own theology. Nor was the unity of the Supreme Being ousted from the Christian creed by the force of reason, but by the sword of civil government, wielded at the will of the fanatic Athanasius. The hocus-pocus phantasm of a God like another Cerberus, with one body and three heads, had its birth and growth in the blood of thousands and thousands of martyrs. And a strong proof of the solidity of the primitive faith, is its restoration, as soon as a nation arises which vindicates to itself the freedom of religious opinion, and its external divorce from the civil authority. The pure and simple unity of the Creator of the universe, is now all but ascendant in the eastern States; it is dawning in the west, and advancing towards the south; and I confidently expect that the present generation will see Unitarianism become the general religion of the United States. The eastern presses are giving us many excellent pieces on the subject, and Priestley's learned writings on it are, or should be, in every hand. In fact, the Athanasian paradox that one is three, and three but one, is so incomprehensible to the human mind, that no candid man can say he has any idea of it, and how can he believe what presents no idea? He who thinks he does, only deceives himself. He proves, also, that man, once surrendering his reason, has no remaining guard against absurdities the most monstrous, and like a ship without rudder, is the sport of every wind. With such persons, gullability, which they call faith, takes the helm from the hand of reason, and the mind becomes a wreck. I write with freedom, because, while I claim a right to believe in one God, if so my reason tells me, I yield as freely to others that of believing in three. Both religions, I find, make honest men, and that is the only point society has any right to look to. Although this mutual freedom should produce mutual indulgence, yet I wish not to be brought in question before the public on this or any other subject, and I pray you to consider me as writing under that trust. I take no part in controversies, religious or political. At the age of eighty, tranquillity is the greatest good of life, and the strongest of our desires that of dying in the good will of all mankind. And with the assurance of all my good will to Unitarian and Trinitarian, to Whig and Tory, accept for yourself that of my entire respect. TO MR. EDWARD EVERETT.