I want to know what God says about religious laws in a secular nation (the US is a secular nation that has been heavily influenced by Christian beliefs), as well as what God says about utilizing religious laws in a secular nation that might be flawed laws. What I mean by flawed laws - for example, Catholics believe that men should not use contraceptives just as women should not use them (condoms). Protestants don't share that belief, so what would God say about a law that states men cannot use condoms anymore?
God appointed judges under him to rule Israel. He didn't separate himself from Israel's government until the people demanded an earthly (secular in the sense of bloodlines) King and see what that got them. Secular government is not God's idea.
If with your Catholic/Protestant question you are saying religious laws are sometimes unclear I would place the same failings on secular law. Off the top of my head I know our president just "decided" not to enforce DOMA when he is supposed to be the executive branch. Then there was that whole recess appointments debacle. My point is only to say secular law fails to be clear in things, as much if not more than God's law, not to go off topic into arguing examples. To understand if questions of law are in agreement with existing law one must understand the intent. Precedents cannot always provide answers because there will not always be one or it may not conform. Therefore if your government is secular based people, through sin, will find legal ways around law to serve personal desires because that government cannot answer the question "why". Religious based law will and has been twisted in the same manner but with it you still have the intent, the why, or the source to go back to (
Luke 6: 1-11). Religious based law can have a reformation, a getting back to God, where do you go with secular law? What are governments but men and what happens to men without a solid foundation (
Luke 6: 46-49)? For example ask the question at the root of the argument on abortion (which is largely ignored by politicians and media). What makes a human being a human being? This is why you get...
Pro-choice: The people stopping abortions are infringing on a woman's constitutional rights because unborn children are not human.
Pro-life: The pregnant mother is infringing on men and women's constitutional rights because unborn children are human.
You cannot just "enforce" abortion laws either way without answering the root. The law would appear to the loser to be contradicting other laws. The "what makes you human" argument must be resolved but secular law cannot do it. That's because if what makes "you" is reduced to something measurable by science then a person's value becomes finite in the world. Diamonds are rarer, computers are smarter, apes are stronger what then is the value of man? If your value is dictated purely by the earthly world so will your place be in it. It
must because secular law is purely earthly you must be defined as purely earthly or it wouldn't be secular law. To achieve a secular, pure numbers, no religion, government, it cannot ask why. It can only enforce but without understanding the underlying intent, the why, one cannot interpret law to enforce it properly. You need a religious (Christian) basis in law, secular or otherwise, or you will have problems.