That would probably be the easiest thing to do, but it doesn't match up well with people's attempts to live their lives according to their faiths. To take one example, if there are laws that require children to be in school until they're 18, why do we allow Amish to be an exception to that law and pull their kids out at 14? Why do we allow Christian Scientists to not have their children vaccinated before attending public school? Why do we allow tax exemptions for religious groups? I don't think it's possible to make the line between church and state as clear and distinct as a lot of people seem to want it.