This "republican theology," often being preached under the auspices of Christianity, Dr. Gregg Frazer has termed "theistic rationalism." And many of those preachers, consequently, were not "Christians" as historically defined, but according to Frazer, "theistic rationalists." When preachers embraced Arminianism and then unitarian Christology, they ceased being "Christians" as historically defined. However, some orthodox preachers likewise peddled a-biblical "theistic rationalist" ideas while managing to remain orthodox. Preachers such as Ezra Stiles (President of Yale, 1778 to 1795), Samuel Langdon (President of Harvard, 1774 to 1780), and Bishop James Madison (one of the first Episcopal Bishops in the US and cousin to Founder and President James Madison) were probably orthodox Trinitarian Christians. Yet, when they argued the cause of revolution or republicanism, they turned to this synthesis of a-biblical Whig and rationalist ideas that distorted the biblical record as these foreign ideas were incorporated into the Bible's text. In short, even orthodox Christians posited theistic rationalist principles from the pulpit to justify American Founding ideals.
It's important to note that the theistic rationalists considered themselves "Christians" and the orthodox Christians like Stiles, Langdon and Bishop Madison were friends with theistic rationalists Jefferson, Franklin and Washington and fell ardently into line with their enlightenment rationalist project. As Thomas Jefferson wrote of Bishop James Madison:
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.
-- To Dr. Benjamin Rush September 23, 1800.
And about what did this "man of truth," orthodox Christian that he probably was, preach? Sandoz informs us that Madison was "[a] strong advocate of independence, he went so far, we are told, as to speak of the republic—rather than kingdom—of heaven. He served as the captain of a militia company of his students and saw considerable action during the Revolution." Likewise the orthodox Christian Samuel Langdon preached a sermon entitled "THE REPUBLIC OF THE ISRAELITES AN EXAMPLE TO THE AMERICAN STATES." The problem is the Bible teaches the Israelites had a theocracy not a republic and that there is a "kingdom" not a "republic" of Heaven. Indeed, "republicanism" traces entirely to our pagan Greco-Roman heritage. These preachers "read in" republicanism to the biblical record.
Further these "rational Christian" republicans -- unitarian or trinitarian -- were likely enthusiastic supporters of the French Revolution, obviously before the mess. As Enos Hitchcock put it in a 1793 sermon entitled "AN ORATION IN COMMEMORATION OF THE INDEPENDENCE OF THE UNITED STATES OF AMERICA":
As Americans, we must either renounce that which is our boast and glory, or warmly wish success to the great principles of the French revolution—principles founded on the equal liberty of all men, and the empire of the laws. As rational beings, and as Christians, we should recollect, that from partial evil, it is the glory of the Supreme Ruler to bring forth general good; and that, as inspiration expresseth it, “He makes the wrath of man to praise him; but the remainder of wrath will he restrain.”
The present war in Europe has a further object than the subjugation of France. It is a war of kings and despots, against the dearest rights and the most invaluable privileges of mankind. Should the combined powers succeed against France, and the re-establishment of monarchy there exist among possible events, what security have we, that the same attempt will not be made to restore monarchy in this country? Has not united America led the way? And may she not boast, with an honest pride, of the influence of her example in exciting the attention of many nations to their natural and civil rights? With what freedom of thought—with what enlightened and ardent philanthropy, has she inspired many of the nations of Europe!
So was Hitchcock a Christian? He called himself one and presented his ideas under the auspices of such. But as Sandoz notes, "His theology moved from Arminian to Unitarian over the years,..." He was what Dr. Frazer would term a "theistic rationalist."
Still orthodox Trinitarians like Ezra Stiles likewise supported the French Revolution with rhetoric that mixed biblical texts and a-biblical enlightenment rationalism. Indeed some orthodox Christians joined unitarians Joseph Priestley and Richard Price in their notion that the French Revolution would usher in a "millennial republic." Tunis Wortman was one of Jefferson's "Christian" supporters who tried to argue Jefferson was really a Christian. I don't know exactly Wortman's personal theology (whether it was orthodox), but he was another notable preacher who fervently supported the French Revolution and thought it would usher in a millennial republic. Sandoz notes "[b]y 1801 disillusionment had set in." Stiles died in 1795 without showing signs of disillusionment over his support of the French Revolution.
There were a number of notable orthodox whose theology was more resistant (though not entirely resistant) to the Enlightenment rationalist appeal. Men like Timothy Dwight, William Linn, Jedidiah Morse, John Mitchell Mason and Jonathan Edwards, Jr. They were likely to publicly complain about the US Constitution being a "Godless" document. They tended to be Federalists and most of them "smelled" Jefferson as an infidel. However, they were apparently unaware that John Adams' personal unitarian theology was almost exactly the same as Jefferson's. They viewed such unitarianism as a halfway house to infidelity. And they also tended to engage in wishful thinking that Washington was an orthodox Christian like they were. Respectable scholars such as Michael Zuckert and non-respectable ones like Gary North have noted these orthodox -- who by in large supported the Founders' "republican" project -- arguably were the victims of a "bait and switch." That is they were sold a project that presented itself with Christianity but was really foreign to the historic orthodox practice of the faith.
A sermon by Jonathan Edwards, Jr. son of the Edwards of the Great Awakening fame illustrates the tension between orthodox biblical ideas and the a-biblical enlightenment republican ideas that captured the minds of America's Founders and the preachers in whom they found support. Edwards defends the historic practice of Christianity against paganism and "infidelity." Particularly telling is that Edwards slams the very Greco-Roman paganism for which America's Founders and many of the patriotic preachers had an affinity.
I shall take notice of only one more vice of the antient heathens, that is suicide. This was recommended by many philosophers, as an heroic act of virtue, and was practised by some of the highest fame, as by Zeno the founder of the sect of the Stoics, by Cato of Utica, and by Brutus. No wonder if under such instructors and such examples, suicide was very common among the antients. Beside the wickedness of this in the sight of God, the ruinous tendency of it in a political view is manifest on the slightest reflection. By this one vice not only any man may deprive the state of his aid and throw his family and dependents on the public; but the most important citizens, by throwing away their own lives in the most important and critical moment, may greatly endanger and entirely overthrow the commonwealth. What if our Washington, or the most wise and influential members of our congress, had destroyed themselves in the most critical periods of the late war?
Edwards is apparently unaware that America's Founders modeled themselves after these figures from pagan antiquity and shaped their sense of honor and virtue after them. Edwards' invocation of Washington is particularly inapt. Joseph Addison's Cato was Washington's favorite play; he had it performed for his troops at Valley Forge to rally them. And that play inspired many other Founders, some of whom were orthodox Christians (like Patrick Henry) and some of whom were not. Cato's suicide is central to its message; he's a man who committed suicide rather than submit to the tyranny of Caesar.
The prime message of the play was "given me liberty or give me death," certainly the source of Patrick Henry's famous quotation. The question is not whether Washington et al. would have destroyed themselves during critical periods of the war, but if Washington lost the war and faced either British tyranny or the choice of death by suicide, which would he choose? (Of course he would have preferred to have died in battle.) Given the profound influence that play had on Washington, arguably he would have done the very un-Christian thing of take his own life rather than submit to King George III's tyranny just as his hero did. That Jonathan Edward's Jr. doesn't understand this shows that this pagan worldview that shaped the Founders' sense of virtue went over the heads, as it were, of the orthodox who thought republican ideas went hand in hand with orthodox biblical Christianity. This refusal to "see" the pagan worldview of the American Founding's enlightened republican project is also key to perpetuating the "Christian America" myth today.