I understand why a Mormon would believe in the theology of Langdon's address, precisely because of when and where Mormonism was founded. Mormonism incorporates various eccentric late 18th Century Americanist historical dynamics into its theology. For instance, they believe as a matter of doctrine that America’s Constitution was a divinely inspired document.After being president of Harvard, Samuel Langdon was a delegate to New Hampshire’s ratifying convention in 1788. The Portsmouth Daily Evening Times, Jan. 1, 1891, accredited to Samuel Langdon: “by his voice and example he contributed more perhaps, than any other man to the favorable action of that body” which resulted in New Hampshire becoming the 9th State to ratify the U.S. Constitution, thus putting it into effect. There Rev. Samuel Langdon gave a speech titled ‘The Republic of the Israelites An Example to the American States, June 5, 1788, which was instrumental in convincing delegates to ratify the U.S. Constitution:
Instead of the twelve tribes of Israel, we may substitute the thirteen states of the American union, and see this application plainly offering itself, viz. – That as God in the course of his kind providence hath given you an excellent Constitution of government, founded on the most rational, equitable, and liberal principles, by which all that liberty is secured … and you are impowered to make righteous laws for promoting public order and good morals; and as he has moreover given you by his Son Jesus Christ…a complete revelation of his will … it will be your wisdom … to … adhere faithfully to the doctrines and commands of the gospel, and practice every public and private virtue.”
Because orthodox Christianity was founded one thousand and some hundred odd years before America and thus teaches nothing special about America as a particular country, serious scholars of political theology, many of whom devoutly believe in orthodox Christianity and try to get the faith right, understand these sermons and their premises differently.
I’m thinking of among others Drs. Mark Noll, Nathan Hatch, George Marsden, Robert Kraynak, Gregg Frazer and John Fea.
The notion that Ancient Israel had a “republic” that could serve as an example to the newly established “United States” is as much a creation of Whig and Enlightenment thought as it is “biblical.” And since the concept of a “republic” actually derives from the Ancient Greco-Roman tradition (for whom America’s Founders had an affinity) arguably that ideological strand gets dragged in too here.
As Dr. Frazer observes on the content of this and related sermons:
[They] seem to depict God’s role as something similar to Rousseau’s legislator; He disinterestedly established the foundational law for the benefit of society, but did not live under it. In their version and consistent with democratic theory, God established it all [quoting Langdon’s sermon] “for their happiness” rather than to achieve the fulfillment of a sovereignly determined plan. By their account, God submitted the laws to the people for their approval and acceptance (as per Rousseau’s legislator).
— Frazer, PhD thesis, pp. 393-94.If I remember correctly, Dr. Frazer claims Samuel Langdon was a "theistic rationalist" not a "Christian." This may not be correct insofar as the "theistic rationalists" were not orthodox on matters like Trinity and other traditional doctrines of the faith. Langdon may well have been an orthodox Trinitarian Christian.
One thing Dr. Frazer claims about the "theistic rationalists" is that their God (unlike the "Christian" God) was man made; the key Founders and those who influenced them remade God in their image. So Rev. Langdon may have been an orthodox Christian. But it seems he's still revising the biblical record.
I don't think there's any question that Elias Boudinat was an orthodox Christian. But he did something very similar when he claimed that Native Americans were the lost tribes of Israel. And as with the notion that the Ancient Israelis had a "republic," this notion too was originally posited by European Rabbis.