Uh, prohibited by what exactly? Oh, by an interpretation of the constitution, which can be changed. If the people want to they can change the constitution in whatever way they want, there is a framework for doing so.
Further, regardless of what the government can or can't do in terms of legislation, people are free to push for whatever changes they want, as long as they don't break any laws in doing so. What you think of their goals and whether they would be constitutional is irrelevant. You need to take a course in civics 101, you clearly don't have even a basic understanding of how things work.
There doesn't need to be any secular argument. In fact, there doesn't need to be any argument at all. Legislation is passed, end of story. The courts then get to decide if that legislation is constitutional or not. Since the constitution itself can also be changed, there is literally nothing that is set in stone in terms of legislation. Also, you don't seem to understand the concept of a framework for change. Again, civics 101.