Or, as I said before, "turning a bunch of commandments into one."
We've already gone through the first five of the "ten commandments" - and let me remind you that not only are they not actually numbered in the original, or the only set, but they're not even called that. (A later set are, dealing with religious laws - things like how not to boil a goat.)
The point of them not being numbered is going to be important to remember here, and you'll see why in a moment. First, the list:
6.Thou shalt not kill. (Murder.)
7.Thou shalt not commit adultery.
8.Thou shalt not steal.
9.Thou shalt not bear false witness against thy neighbour.
shalt not covet thy neighbour's house, thou shalt not covet thy
neighbour's wife, nor his manservant, nor his maidservant, nor his ox,
nor his ass, nor any thing that is thy neighbour's.
Yes, the last five all at once.
Now, these are pretty straightforward (at first.) But tell me, do you really think there needs to be divine inspiration to say "Don't murder, don't screw your neighbor's wife, don't steal things?" Regardless of location, time or the like, every civilization comes up with these - they're fairly commonsense, basic laws on keeping a society intact. These existing is not proof either of a god or of Christianity being a basis for American laws - and frankly I think most Jews, or anyone else, would find the notion that they couldn't figure out "murder = bad" without heavenly declaration insulting.
However, in context these... are odd. Especially given what comes after (Exodus 21, for instance, goes on about how to buy and treat a slave, how to sell your daughter and the like - again, hardly moral - and a number of things that lead to "you will kill him." Then a big pile of stuff about oxen, and if someone rapes a woman, he can buy her - basically bribe her father to marry her. And by Exodus 23, God's saying he'll help out in genocide and in stealing land. Forgetful, I suppose.)
But if we look at these as just "your fellow tribesman," which means we have to combine them - and again, lack of punctuation in the original - they fall together better. The word "neighbour" here does mean, basically, "your fellow jew." Caananites were not "neighbors" in context. So we have:
"You shall not murder, commit adultery, steal or bear false witness against your fellow tribesman. You won't want their house, wife, slave or livestock." (Note, ladies, the wife put there with the possessions.) Which, if we're talking morality... is a lot less "moral." (Don't kill your tribesman, but hey, those guys over there, go nuts.)
Again, I don't think I need to go into American law here - as these, once more, are just common sense. And as put in secular law, there's no limitation. No, you're not allowed to murder or steal from your fellow American. Nor are you allowed to from a non-American. You just aren't allowed to steal, murder, etc.
As far as the tenth - it's ridiculous, as it's forbidding a thought crime. "Don't even think these things!" Well, guess what.. you just thought them by considering and naming them, by some interpretations. Regardless, no legislation has been passed to forbid you from thinking things - that would be illogical and just plain silly, not to mention unenforceable.
Besides, we're generally capitalist here in the US. Wanting things is seen as good. If your neighbor has a really nice car, you'll want one - and maybe work a bit harder and save to afford it.
In the end, though, I think it's fairly evident that there's zero support for the ten commandments having anything to do with our founding documents - and that anyone arguing otherwise has probably read neither.