Law is essentially moral in both nature and origin. It would be hard, and a bit too circuitous, to argue that laws against theft and murder are not essentially moral positions. These positions are enforced legally in societies that, presumably, you or I or anyone would want to live in.
It is an abstract (and highly modern) notion of law which allows one to state that law is not necessarily moral. At its root, law is moral; and if a law isn't grounded in moral principles, then it ought not be law.
Now, people cannot look into the state of the heart. We are not talking about piety or sincerity, we are talking about the basic moral nature of protecting people from theft, murder, slander, etc. The law is an objective moral standard for those, and there are many many who fall into this category, who do not intuit the "golden rule."
Entire civilizations have been and are being built on principles other than the "golden rule," such as those the armies of Genghis Khan operated under, or the Vikings, or the Nazis, or the Soviets. To say that law is not moral in nature, or to imply that people don't need these laws, is to overlook a great deal of, not just the accidents or mistakes of particular groups who have betrayed their own moral law, but of the large and powerful groups of people throughout history who have an alien moral law which purposely burns, rapes, and pillages in complete agreement with their (false) moral law.
As such, no law is or can be amoral in nature, even if from certain perspectives a law in question may seem distant from its basic moral principle.
All legislation is fundamentally moral in nature. Law is unavoidably moral. This is why the question, "which morals?" is so pertinent. The problem today is that people think they can legislate in a morally neutral way, but that itself is a moral position.
In other words, of course we should legislate morals, like morals that forbid murder and rape. We as a people need to know our criteria for the morals we choose to legislate, and where we get these criteria, and not pretend we can legislate in a moral vacuum.
If someone says I am morally wrong to impose my morals on others, and that they are morally right to not impose, then they are arguing morally; and if someone tries to legislate that, they are legislating their morality over and against mine, imposing their moral vision of society onto me.
What gives them the moral right to legislate their morals if their very reason for disagreeing with me is that I am legislating my morals?
The fervor for secularity omits very real and very severe truths, because the idea of the secular borrows much of its ethics from religion. A secular culture does not need to be tolerant, and nothing but religion actually requires tolerance. And even if people regularly fail to live up to their religion's principles, it only proves the necessity for those religious principles because without them there would be no philosophical check against secularity becoming the cruelest and most inhuman experiment ever invented.
And so, as the secular continuously tries to cut itself off from its religious roots, it will cut itself off from its humanity. A separation of Church and State requires a Church to be separated from, otherwise the State becomes its own wicked and distorted version of a Church - minus a moral compass.
