As applied to laws in this country, it means no such thing. Our laws are based on the moral teachings of Christianity, and not those of Islam, Zoroastrianism, or Thuggee.
Yes--I've lost count of the sleepless nights I've spent, worrying about the serious threat to the American way of life posed by the fact that the murder laws of all fifty states give effect to one of the Ten Commandments. Just imagine!
Of course you are, to the extent those religious tenets are reflected in criminal laws. If some savage comes here from a godforsaken land and brings with him the belief that it's fine to rape any unaccompanied woman whose clothing reveals a lot of skin, that savage nevertheless is obligated to abide by the rape laws of whatever state he is taking up space in. The U.S. having developed as a primarily Christian nation, and having derived its laws from those of England, another primarily Christian nation, the laws the alien savage in my example must abide by inevitably reflect Christian morality. Same for our laws against burglary, adultery, prostitution, robbery, polygamy, arson, and so on.