@Walter Hinteler,
In my opinion, not only laws have a religious background but anything in daily life.
Numa Pompilius, the "agent of the Gods", gave us days, months, and years. (Actually now, we are even in "Catholic times" > Gregorian calendar.)
Who bothers about that and why not make it secular?
I think that
secular in the sense used nowadays in the USA's context has a different meaning in Japan, India, Yemen, an Austrian Alpine village, or the Brazilian rainforest. And different to what it meant (or might have meant, if people had known the term then), one hundred, five hundred or four thousand years ago.
Really interesting is, to research the relation of the
Law of the Vatican City State to the religious laws embodied in Canon Law. And then decide, what is secular, what is relgious.