The Father of Psychiatry, Benjamin Rush (1746-1813), signed the Declaration of Independence and was a delegate to the Constitutional Congress. Rush was good friends with both Thomas Jefferson and John Adams. Despite his universalist beliefs, he is a favorite of David Barton and other Christian Nationalists because he was a founder who articulated many Christian interests and pursuits.
I thought of Rush after reading a World Net Daily article today by John Aman criticizing Coral Ridge Presbyterian Church pastor Tullian Tchividjian for avoiding culture war issues in the pulpit. Specifically, I thought of Benjamin Rush’s response to Thomas Jefferson’s famous “altar of God” letter to Rush. Michael Coulter and I deal with this exchange between Jefferson and Rush in our book Getting Jefferson Right: Fact Checking Claims about Our Third President.
In his article, Aman cited Barton and others to claim preachers should preach about political issues. However, Rush told Jefferson in his October 6, 1800 letter, Saint Paul would tell modern preachers to “cease from your political labors.” Rush’s position is not unlike Tchividjian’s.
From Getting Jefferson Right:
On August 22, 1800, Jefferson’s friend and fellow signer of the Declaration of Independence, Benjamin Rush, wrote to Jefferson asking for a clarification of his religious views. At their last meeting, Rush had extracted a promise from Jefferson to read William Paley’s book, A View of the Evidences of Christianity. In addition, Jefferson apparently promised to explain his “religious Creed.” As of that writing, Jefferson had not complied with the request.
You promised me when we parted, to read Paley’s last work, and to send me your religious Creed.–I have always considered Christianity as the strong ground of Republicanism. Its Spirit is opposed, not only to the Splendor, but even to the very forms of monarchy, and many” of its precepts have for their Objects, republican liberty and equality, as well as simplicity , integrity and Economy in government. It is only necessary for Republicanism to ally itself to the christian Religion, to overturn all the corrupted political and religious institutions in the world. I have lately heard that Lord Kaims became so firm a Beleiver in Christianity some years before he died, as to dispute with his former disciples in its favor. Such a mind as Kaims’ could only yeild to the strongest evidence, especially as his prejudices were on the other Side of the Question. Sir John Pringle had lived near 60 years in a State of indifference to the truth of the Christian Religion.–He devoted himself to the Study of the Scriptures in the evening of his life, and became a christian. It was remarkable that he became a decided Republican” at the same time. It is said this change in his political principles exposed him to the neglect of the Royal family, to whom he was Physician, and drove him from London, to end his days in his native Country (p 318) 
Apparently, by telling him of those who converted to Christianity later in life, Rush hoped to convince Jefferson that it was not too late for Jefferson to turn to orthodox Christianity. Jefferson wrote back on September 23, 1800 saying that time constraints had prevented him from honoring his pledge. Jefferson had been thinking about it and wanted to have adequate time to write a complete answer. To Rush, Jefferson wrote:
I promised you a letter on Christianity, which I have not forgotten. On the contrary , it is because I have reflected on it, that I find much more time necessary for it than I can at present dispose of. I have a view of the subject which ought to displease neither the rational Christian nor Diests, and would reconcile many to a character they have too hastily rejected. I do not know that it would reconcile the genus irritabile vatum( 2) who are all in arms against me. Their hostility is on too interesting ground to be softened. The delusion into which the X. Y. Z. plot showed it possible to push the people; the successful experiment made under the prevalence of that delusion on the clause of the Constitution, which, while it secured the freedom of the press, covered also the freedom of religion , had given to the clergy a very favorite hope of obtaining an establishment of a particular form of Christianity through the United States; and as every sect believes its own form the true one, every one perhaps hoped for his own, but especially the Episcopalians and Congregationalists. The returning good sense of our country threatens abortion to their hopes, and they believe that any portion of power confided to me, will be exerted in opposition to their schemes. And they believe rightly: for I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. But this is all they have to fear from me: & enough too in their opinion, & this is the cause of their printing lying pamphlets against me, forging conversations for me with Mazzei, Bishop Madison, &c., which are absolute falsehoods without a circumstance of truth to rest on; falsehoods, too, of which I acquit Mazzei & Bishop Madison, for they are men of truth.– But enough of this. It is more than I have before committed to paper on the subject of all the lies which have been preached or printed against me. 
Jefferson does not address Rush’s proselytizing but instead described his frustration with his critics and his opposition to establishment of Christianity “through the United States.” Rush then wrote back on October 6, 1800 in order to clarify his views on religion and the state.
I [Rush] agree with you [Jefferson] likewise in your wishes to keep religion and government independant of each Other. Were it possible for St. Paul to rise from his grave at the present juncture, he would say to the Clergy who are now so active in settling the political Affairs of the World: “Cease from your political labors-your kingdom is not of this World. Read my Epistles. In no part of them will you perceive me aiming to depose a pagan Emperor , or to place a Christian upon a throne. Christianity disdains to receive Support from human Governments.” From this, it derives its preeminence over all the religions that ever have, or ever shall exist in the World.  (emphasis added)
Throckmorton, Warren; Coulter, Michael (2012-05-01). Getting Jefferson Right: Fact Checking Claims about Our Third President (Kindle Locations 2267-2328). Kindle Edition.
Rush believed that Christianity supported the republican impulse. He did not express support in this letter for clergy being active in “political labors.” Rush paraphrases St. Paul as declining to work toward political positions for Christians. It appears that Tchividjian and Rush have something in common.