Before the split between east and western christianity there was even more division within the church as there was a pope for every region, [roman pope, greek pope, lebanese pope, egyption pope and just some others.] Then the roman pope decied that he quite fancied ruling the entire world and that jesus was god, which is silly as if jesus is co-eturnal and knew all along that would be resurrected then the sacrifice of the cross means NOTHING, so all the other popes [i.e. the east.] made it quite clear that rome had nothing to do with them and then got arab'd before they had a chance to spread orthodoxy to more countries so that Rome won out and became the christian centre for the world and went on crusading on the eastern church for the next couple hundred years.
In reference to Civ.
The point im trying to make is, If you were to do that then i think that a wonder called the First 'state-religion-adjective' Council which would cause he creation of a new religion 'founding-civ-adjective state-religion' in that city and give a 50/50 chance of all cities with the state relgion present within your borders losing their state-relgion and gaining the new religion.
or taking Christianity as the example and the Civ being Greece, and i will just copy paste as it works and i cant be arsed retyping that
The point im trying to make is, If you were to do that then i think that a wonder called the First Christian Council which would cause he creation of a new religion Greek Christianity in that city and give a 50/50 chance of all cities with Christianity present within your borders having their Christians convereted to Greek Christians.
An almost idenitcle religion with recoloured churches and symbol.
And this idea is growing on me since i tought of it a few moments ago, and it could even be a mod for straight Civ BTS not just the Scenario in discussion.
although most likely not unless someelse does it.