It's the Roman Catholic Church, not the Republican Catholic Church or the People's Revolutionary Socialist Democratic Catholic Church. Its rigid hierarchy and its centralizing instincts are almost entirely due to the fact that it became the state religion of the Roman Empire over 1,600 hundred years ago. And the pope is still, in essence, the emperor.
How Roman are the traditions and instincts of the church that Pope Benedict XVI has led for the past seven years? Well, one of his titles is "Pontifex Maximus," usually translated from the Latin as "Supreme Pontiff."
That was the title of the high priest of the old Roman (pagan) state religion under the Republic. When Rome became an empire, the emperors took it over, starting with Augustus. And somewhere in the fifth or sixth century — the timing is not clear — the title was transferred to the Christian bishop of Rome, who had become the head of the new state religion, Christianity.