Several hundred years passed between Leviticus 20:10 (“I order you to put to death all the adulterers”) and John 8:7 (“…but only by those with no sin, which is no one.”). In the hundreds of years between this mandate and its “minor” clarification hundreds, if not thousands, of men and women were put to death. Stoned to death, in most cases.
Today, societies still based on that kind of morality (and there are several) are rightly considered barbaric. That behavior wasn’t moral then, and it isn’t moral now. And anyone who makes that kind of commandment to his followers, we throw in jail and refuse their parole.
We don’t base our astronomy, chemistry, biology, medicine, physics, or any of our current understanding of the universe on blind unquestioning belief in any books on those topics written several millennia ago. By the same token, we have to recognize that we don’t base our morality on those books either, regardless of any claims of their supernatural origin. We can’t. We definitely don’t base our legal system in the US on it, and until you can show me the laws against graven images, I don’t think you can claim so.
We base our legal system and our morality on common, secularly-derived understanding of what is right, and reaching a mutual understanding of the type of society we would all choose to live in. It’s not divine inspiration, it’s definitely not biblical interpretation; it’s our use of reason. And reason is what allows us to look at these old books, understand their all-too-human and oh-so-fallible origins, pick the elements that are still OK and throw away the unnecessary rest; as it turns out, that discardable flotsam includes all the parts of the text that claim that our reason and our morality come from anywhere outside of ourselves.