Excellent, on-topic post. To secure religious freedom, the Founders knew well that the government could not be entangled with religious tribalism.
Yet those Ten Commandments on the monument are pretty much acknowledged by all of the hundreds of Protestant, Catholic and even Judaic groups --a point of
commonality, not division.
Acknowledging those commandments as the basis of Western morals and legal systems (and the fundamentals for avoiding trouble in any culture) isn't far off base, either.
So the government was to uphold the God-given Right of people to worship as they chose, and was proscribed from interfering with that worship. Nor was the government allowed to use the religion of a person eligible otherwise for office to disqualify them from that office.
Unlike the secular humanists and those who decry the Bible, I don't see it as a bunch of restrictions, the "Thou Shalt Nots" people whine about. It is more like a user's manual for humans, with examples.
Now, while many might not see it that way, I don't reckon they check their oil in their car very often, either--but if they do, maybe they will begin to understand that not doing the things that Scripture cautions against, and doing the things it says to do often, even thousands of years later, produces desirable results, good health, even happiness.
Fight that all you want, use cheap oil, redline the engine frequently, and you just won't like the results in the long run.
When we say something is wrong, we say it because of experience or advice, we know that. We'd be remiss not to let people know, just like not letting them know they had a low tire. If you want to drive on that flat, it's your car, but I'm not going to let you recommend it to someone else, either, without piping up. Just as when I see people doing things I consider morally wrong, I can't approve, I will say something.
People are still free to choose to ignore that advice, but the results are on them.