Jesus started it.
Catholics did not invent Christianity.
Believers in Christ were first called Christians at Antioch, shortly after Christ's death. It was the unbelievers who gave them this name, meaning "little christs" because they said they were like little copies of Jesus Christ walking around.
It was meant as mockery, but is the highest praise I could ever receive, to be like Christ.
That was before the Catholic church, as it is today, existed, though Catholics say that the church of today can be traced back to those times.