A commenter named "Rap" -- who apparently has Christian Nationalist sympathies -- left the following comment at Positive Liberty:
Here’s a thought, why not let the founders speak for them selves? Why should one “expert” or another edit what they actually said? Oh, I know…because it doesn’t fit in the elitist progressive agenda. After all they know more about the founders than the founders did of themselves. For example George Washington said to his mother after a big battle at fort Necessity and a new appointment:”The God to whom you commended me, madam, when I set out upon a more perlious errand, defended me from harm, and I trust He will do so now. Do not you?” Oops! The ACLU is going to be all over him! Wait…he’s dead. So I guess they will just keep hiding what he and the other founders said from our children!
I responded, yes by all means, let the Founders speak for themselves. Not phony “experts” like David Barton or Peter Marshall. Or this commenter him or herself. The quotation s/he tried to pass is nowhere to be found in Washington's official writings.
I did a google search and found it in some 19th and early 20th Century sources like the notoriously shoddy, revionist book George Washington, The Christian.
On a related note, Clayton Cramer encounters a bogus GW quote:
Government is not reason; it is not eloquent; it is force. Like fire, it is a dangerous servant and a fearful master.
As Cramer notes:
The problem is that when I search the George Washington Papers at the Library of Congress--it isn't there. Searching books.google.com, the earliest example is from Christian Science Journal in 1902--and there's no citation.