Washington did read sermons and corresponded with various religious figures, and almost always thanked them for their work in polite, perfunctory ways. Lillback constructs an argument that when Washington says positive things about the work of a particular religious figure, Washington essentially "internalizes" those beliefs. Further, Lillback argues all of these figures/sermons were "orthodox." Hence GW was "orthodox Christian." But, that's not the case. Most were orthodox because most Christian Churches were. Some of the notable orthodox figures for whose work Washington had kind words include William Linn (one of Jefferson's slanderous pious clergy enemies), Jedidah Morse and Timothy Dwight (they were hard core orthodox). Typically such figures or their cohorts would, unrequested, send Washington their sermons and GW would reply with a polite thanks, got it, very nice. The following to Rev. REVEREND ZECHARIAH LEWIS regarding the work of Timothy Dwight (President of Yale, and professed enemy of "infidelity") is typical:
I thank you for sending me Doctr. Dwights Sermons to whom I pray you to present the complimts. of Yr. etc.
Yet, I've stumbled upon a number instances where Washington gives the same perfunctory nods to explicitly UNORTHODOX figures whose work expressed heterodox content.
For instance, Richard Price, a British Whig divine who profoundly influenced the American Founding. He was an open Arian in the late 18th Century. He was sort of an Arian counterpart to his Socinian friend, the Rev. Dr. Joseph Priestley, another British Whig divine who profoundly influenced the American Founding.
Washington expressed his approval of Richard Price's work in a letter to BENJAMIN VAUGHAN, February 5, 1785:
Sir: I pray you to accept my acknowledgment of your polite letter of the 31st. of October, and thanks for the flattering expressions of it. These are also due in a very particular manner to Doctr. Price, for the honble mention he has made of the American General in his excellent observations on the importance of the American revolution addressed, "To the free and United States of America," which I have seen and read with much pleasure.
And you can read the contents of that sermon here. [I blogged about in in detail here.] The sermon professes to be "pro-Christian," and asserts Jesus Christ as Messiah and Savior. For instance it holds:
When Christianity, that first and best of all the means of human improvement, was first preached it was charged with turning the world upside down.
Yet, it is also explicitly anti-Trinitarian [again Price was an avowed Arian Unitarian]. Price attacks the "Athanasian creed" which is the quintessential statement of Trinitarianism:
Perhaps nothing more shocking to reason and humanity ever made a part of a religious system than the damning clauses in the Athanasian creed and yet the obligation of the clergy to declare assent to this creed, and to read it as a part of the public devotion, remains.
The sermon further includes the following pro-unitarian, heterodox sentiments. In the context of arguing religious liberty and equality for all (not just "Christians"), Price asserts:
Montesquieu probably was not a Christian. Newton and Locke were not Trinitarians and therefore not Christians according to the commonly received ideas of Christianity. Would the United States, for this reason, deny such men, were they living, all places of trust and power among them?
So ultimately what can we conclude regarding Washington's positive thoughts about various sermons when he positively reacts in similar ways to the orthodox ideas of Timothy Dwight on the one hand and heterodox sentiments of Richard Price on the other? This is why I argue it is a non-sequitur for Lillback to conclude all of the nice things Washington said about the orthodox clergy and their sermons prove him an orthodox Christian. No. They merely show that he was more "pro-religion" than a cold Deist like Thomas Paine was.
Finally, there are other examples of Washington praising non-orthodox or heterodox ideas. For instance, here I noted Washington's praise for the Universalist Church who denied eternal damnation/asserted universal salvation. He basically said whatever it was he valued about religion for the way it supported republican government the Universalists had it.
Postscript: In the short future I will show more evidence on Richard Price's influence on Washington and many other Founders, including Alexander Hamilton. I will show Price's influence was especially high when the Constitution was being framed and ratified.