However, despite Thomas Jefferson's protestations about his "influences" being non-Biblical, it cannot be disputed that John Locke was one of them.
A great many things which we have been bred up in the belief of, from our cradles, (and are notions grown familiar, and, as it were, natural to us, under the Gospel) we take for unquestionable obvious truths, and easily demonstrable; without considering how long we might have been in doubt or ignorance of them, had revelation been silent. And many are beholden to revelation, who do not acknowledge it.
---Locke, The Reasonableness of Christianity
Here Locke confesses that his work and the work of his contemporaries is heavily indebted to "revelation," which can only be read as "Biblical principles."
Whether or not Jefferson had the same self-awareness (it seems not) as Locke is immaterial. You can't take the Locke out of Jefferson, and you can't take the Bible out of Locke.
The Lord's Prayer survived Jefferson's razor when he created the "Jefferson Bible," where he edited the Good Book and took out all the supernatural stuff.
But is The Lord's Prayer rational? Not by today's standards. Might as well swear by Grabthar's Hammer.
Jefferson is known mostly for his un-self-evident assertion on human rights, the endowed by their Creator thing, an assertion that bears a striking resemblance to the work of St. Robert Bellarmine, a notorious Christian. Jefferson is exactly the type Locke was referring to, "beholden to revelation, who do not acknowledge it."
Now, Locke makes no claim here or elsewhere that the Bible is historically true: even the Jewish medieval philosopher Maimonides excises the miracles from scripture. (We can dispense with Trinitarianism thusly, for the sake of discussion. For one thing, I wouldn't want the government to order everyone to believe Jesus was God. That would defeat the purpose of the whole faith thing, and neither the Father, the Son, nor the Holy Ghost would be pleased, I think.)
But "love your enemy" is not rational, nor is The Lord's Prayer, nor is the 1700-odd years of theology of the "human person" that led up to Jefferson's bold assertion.
We run the risk of turning Locke's statement, and the history of the Bible in western thought, into gibberish if we dismiss whatever we don't like as "irrational."
"Or whatever else was the cause, 'tis plain in fact, that human reason unassisted, failed men in its great and proper business of morality. It never, from unquestionable principles, by clear deductions, made out an entire body of the law of Nature. And he that shall collect all the moral rules of the philosophers, and compare them with those contained in the new testament, will find them to come short of the morality delivered by Our Saviour, and taught by his apostles; a college made up, for the most part, of ignorant, but inspired fishermen."---Locke, ibid.
It's not so much about what Locke himself believed, but the role of Judeo-Christian principles in founding the American republic. What Locke is saying here is that the Bible was further along than philosophy as a moral system.
Whether philosophy-slash-reason has caught up with the Bible is still questionable. I look at ethicist and philosopher Dr. Peter Singer of Princeton University, who believes in consciousness as the primary claim to rights (your dog has more self-awareness than your newborn son or daughter, after all) and I suspect it never will.
Peter Singer is a reasonable man,
So are they all, all reasonable men