Don’t worry if you haven’t, but it is coming to a country near you. It is the opposite of one country, under God, indivisible. This is from a reasonably positive description:
The millet system was developed to protect the rights of the “tolerated clients of the Muslim community” as Ahl al-dhimmi (Bates, Rassam, p. 101) as designated People of the Book in the Quran and institutionalized after the fall of Constantinople by Sultan Mehmet II in 1453. However, the great expanse of the Ottoman Empire also leaves room for each community, geographically and culturally, to interpret and implement the rules and regulations of the empire differently, if they were respected at all. This applies not only to the term but to the millet system as well.
Israel sort of has one now, as do France and Sweden, but these are places which are not Muslim-majority nations. Here is something from a less positive view of the millet system:
I don’t think even at its height though you could say the Ottoman empire had more liberty than the most law governed and tolerant places in ‘Christendom’ and certainly while European thinkers respect the Ottoman system at its height it very much looked like an example of strong orderly monarchy, not decentralised liberty.
This is where things are heading and which the forces of the left are doing all they can to ensure. Not in my lifetime, but if you are young enough, almost certainly in yours.