Let me ask you a question. In today’s pluralistic societies, how to you propose the Church figures out who is married and who isn’t without the state?
Back in the middle ages, the Church kept all the records and everyone was Catholic. In many ways, the Catholic Church was the local bureaucracy.
But today, not only are people from a ton of different religions, but people no longer live where they grew up, nor do they often get married where they grew up. And people marry others from other parts of the country & world now, not just from their home towns.
It’s not like the priest can simply call the neighboring protestant churches and synagogues to figure out if a non-Catholic can marry. And with so many Catholics not marrying in the Church like they are supposed to, a priest can’t trust that he can solely depend on Church paperwork.
So we need the state, because bringing back the banns isn’t really going to work with interfaith and cross country marriages.