I understand what you’re saying but this isn’t a difference of opinion. The seven Churches were all part of one Church. They shared one baptism and originally shared one faith. They were part of one body. That fact that not all ended up that way doesn’t change the fact that Christ founded One Church.
There was no christian church immediately after Christs Resurrection. They were considered an offshoot of the Jewish religion. A jewish sect if you prefer.. Paul was sent to the gentiles, the apostles were only sent to the Jews of the day...they went to temple as they did before Christs Resurrection., just as Jesus did.I am not sure how long after Christ when they started to call themselves Christians. They were followers of Christ, just as today there are people that convert and call themselves Jews for Jesus....I use to watch Zola Levitt’s program He has passed on but his program was informative he talked about what Jesus life was like as a Jew, explained what Seder was and how he came to believe in the Messiah..Used the bible to prove Jesus divinity via the bible...