You said: Funny, I doubt Paul considered himself ‘Catholic’ and certainly did not sign up to all of the Catholic doctrine.
Well, let’s see, Ignatius, Bishop of Antioch, a disciple of the Apostle John, on his way to martyrdom in Rome writes: “Wherever the bishop appears, there let the people be; as wherever Jesus Christ is, there is the Catholic Church. It is not lawful to baptize or give communion without the consent of the bishop. On the other hand, whatever has his approval is pleasing to God. Thus, whatever is done will be safe and valid.” Letter to the Smyrnaeans 8
This letter shows that during the apostolic age the Church is called the Catholic Church.
Which set of Ignatius' writings are you referring to??? The ones where he doesn't mention anything Catholic, or the other one where Catholic is in everything???