Need to study more below the surface and read your history on the Greeks and how they pick up and passed on to the Romans the ancient Babylonian sun gods and system of worship...
'...Pope is a shortened title for Pontifex Maximus. In Greek it means father. The Pontifex Maximus (meaning king of sacrifices or servant to the triads, as well as the "greatest bridge-maker between the gods and men") was the high priest of the College of Pontiffs (Collegium Pontificum) in ancient Rome. It's a pagan title that was incorporated from the Etruscan-Latin polytheistic culture (700 BC) who lived before the Romans. These early people (just like the Romans) had built great temples to the gods and goddess of the day. They also had a pagan triad. Eventually the Etruscans were conquered by Rome.
The title Pontifex Maximus (Pope) is mentioned numerous times by the early Catholic Church fathers (especially by Tertullian), but it was not applied to a Catholic bishop until much later on. The early Catholics said that the Pontifex Maximus was the "King of Heathendom," the evil high priest of the pagan mystery religion of Rome. This post was the most important position in the ancient Roman religion. A distinctly religious office under the early Roman Republic, it gradually became politicized until, beginning with Augustus, it was subsumed into the Imperial office. It's last use with reference to the emperors is in inscriptions of Gratian (reigned 375-383). He was then urged by the Catholic bishops to renounce the cultic Roman title, and instead grant it to their exalted leading bishop over Rome.
Pontifex Maximus is a name that's being used by the Roman Catholic Church clergy today. Though it may be abbreviated into Pope or Papa, yet it's clearly a title incorporated directly from paganism. Interesting to note that the all the pagan pontiffs or popes held that office for life. Exactly like the Catholics Popes. And their cult members met and elected a successor, who after his election became the next Pope or Pontifex Maximus (Dionys. II.22, 73). Just like the election held by the Catholic Church cardinals to choose a new Pope. The Pontifex Maximus was the guardian of the Vestal virgins. The Roman Catholic Church has simply named them Nuns instead. Many historians agree that the idea for the powers of the pope with the College of Cardinals came from the Pagan College of Pontiffs with its Sovereign Pontiff which had no doubt been in Rome from the earliest times, and must have been framed on the order of the original Council of Pontiffs at Babylon. It's also obvious to any historian that while the Catholics have called themselves Christians, they more closely resemble the ancient pagans both in customs and names. Pope Gregory I (601 AD) said in so many words literally, "We must compromise with the pagans in order to further Christianity."...'
http://www.upublish.info/Article/The-Pope--Pontifex-Maximus-/693298
By the time of Emperor Constantine, the Christian religion received imperial sanction and the bishop of Rome became more than just another bishop, and brought in a system of worship from another origin than Christianity.
After the fall of Rome, the Bishop of Rome served as a source of authority and continuity from the old empire but Rome had also been the center of the pagan priests and their temples during the Roman Empire, and they did not go away. The Bishop of Rome, to bring in more converts brought what they were familiar with and allowed the traditional Roman mysteries and deities of solar monism such as Mithras and Sol Invictus and idol worship back into the church, along with its Pagan doctrines, graven images and ceremonies. It renamed the mother goddess and others that were worshiped and brought them into the church at Rome, then with its influence it spread into the other centers of Christianity.