Seems pretty simple to me ~ very straight forward ~ one church, one state, one people, one king ~ Louis XIV did it that way.
I think somebody does not care to use "church" in the sense of "a religious group and/or building where religious practices are observed" ~ on the other hand I regularly use the word "church" RELIGIOUSLY to displace mosque, synagogue, temple and tabernacle in my own speech.
If others take offense, they are free to go pound sand if they wish.
The fact is that in Saudi Arabia there is ZERO churches (or synagogues) open. And there are many mosques open in USA.
The mosque is not something like the church. And it does not need Louis XIV to rule. It already includes key elements of state laws, of political organization, and of a nation.
So while you can try to separate churches from state because churches in their own nature have concept of dual citizenship in Kingdom of Heaven, the mosque started as the conquest and political coup.