Today I was asked:
When did the Roman Catholic church appear as it is today?
Here’s my answer:
When the Roman Catholic Church appeared “as it is today” depends on what is meant by “as it is today.”
The first pope who had the kind of power that the popes had in medieval times (and wish they had today) was Pope Gregory the Great (pope from 590 to 604). The eastern “catholic” churches have never acknowledged the authority of the pope, not at any time in history.
Prior to Gregory, there was a buildup of power. Stephen of Rome is probably the first to claim that he had the right to tell other bishops what to do. He was pope around A.D. 250. No other bishop acknowledged that right, however. In fact, the great bishop Cyprian of Carthage (known as St. Cyprian to the Catholic Church) held a council of 87 north African bishops to specifically reject Stephen’s claim.
By the time of the Council of Nicea, A.D. 325, the pope had authority over the churches of Italy. The bishops of Alexandria and Antioch had similar widespread authority, and Canon 6 of Nicea acknowledges this and lends the council’s approval to that authority.
During the fourth century, after the Council of Nicea, Rome was the place to run for bishops being persecuted by Constantius, the emperor Constantine’s sun. That made the church in Rome even more important than it already was.
In the fifth century, the western half of the Roman empire fell. The bishop of Rome was the only important bishop with authority over a large area that was in the western half of the empire. Slowly, through the late fifth and sixth centuries, the bishop gained more and more secular and spiritual authority among the conquerors of Rome, the barbarians known as the Gauls, Franks, and Goths. This is how Pope Gregory gained authority over all of Europe, which the popes maintained (with greater or lesser success) throughout the Middle Ages until the Reformation.
The best source for this history is actually a Catholic historian. He has a teaching series on the medieval papacy that is put out by the Institute for Catholic Culture. The history he teaches is remarkably honest. His name is Dr. Brendon McGuire, and you can get his history of the papacy recording at http://instituteofcatholicculture.org/media.htm#medieval for free. He’s pretty interesting to listen to.