Well, no. The apostles literally planted the institutional churches themselves, and appointed bishops to run those churches when they were gone. We know Paul did this from the New Testament, and we know the other Apostles also did this because other early Christian writers knew the Apostles personally, or knew people who had been directly trained by the Apostles.

The institution itself was founded by God. It was not something that came later. The epistles in the New Testament weren't written to individuals, they were written as administrative documents to actual church buildings run by actual bishops.

The term "Christian" also didn't come later. It's in the Book of Acts. You're probably thinking of "catholic" which is still very early. About 15 years after the Book of Revelation.