The Roman Catholic church, headquartered in Rome, Italy, has its own powerful City-State, the Vatican. The Roman Catholic church unofficially came into being in 312 A.D., at the time of the so-called "miraculous conversion" to Christianity of the Roman Emperor Constantine but he still worshipped the sun god. Although Christianity was not made the official religion of the Roman Empire until the edicts of Theodosius I in 380 and 381 A.D., Constantine, from 312 A.D. until his death in 337, was engaged in the process of simultaneously building pagan temples and Christian churches, and was slowly turning over the reins of his pagan priesthood to the Bishop of Rome. However, the family of Constantine did not give up the last vestige of his priesthood until after the disintegration of the Roman Empire – that being the title the emperors bore as heads of the pagan priesthood – Pontifex Maximus – a title which the popes would inherit. The popes also inherited Constantine's titles as the self-appointed civil head of the church – Summus Pontifex (Vicar of Christ and Bishop of Bishops).

Prior to the time of Constantine's "conversion," Christians were persecuted not so much for their profession of faith in Christ, but because they would not include pagan deities in their faith as well. Then, with Constantine's emphasis on making his new-found Christianity palatable to the heathen in the Empire, the "Christianization" of these pagan deities was facilitated. For example, pagan rituals and idols gradually took on Christian meanings and names and were incorporated into "Christian" worship (e.g., "saints" replaced the cult of pagan gods in both worship and as patrons of cities; mother/son statues were renamed Mary and Jesus; etc.), and pagan holidays were reclassified as Christian holy days (e.g., the Roman Lupercalia and the feast of purification of Isis became the Feast of the Nativity; the Saturnalia celebrations were replaced by Christmas celebrations; an ancient festival of the dead was replaced by All Souls Day, rededicated to Christian heroes [now Halloween]; etc.). A transition had occurred – instead of being persecuted for failure to worship pagan deities, Christians who did not agree with the particular orthodoxy backed by the Emperor were now persecuted in the name of Christ! "Christianized" Rome had become the legitimate successor of pagan Rome! This is the sad origin of the Roman Catholic Church as it compromised from the very beginning with paganism and in doing so became a cult serving the creature (Mary) more than the creator (Jesus).