Paganism and Catholicism
In order to account for the origin of the Catholic Church–and to discredit it–some Protestants create certain "histories" of Catholicism which hold that the Catholic Church is a corruption of real Christianity.
The most popular of these theories claims that until the Edict of Milan in 313, Christianity was pure. After the Edict, when Christianity became the official religion of the Roman Empire, pagans came into the Church to derive the benefits of being Christian. They came into the Church in great numbers, and to assimilate them, they were allowed to retain their pagan beliefs and practices, which gained a home in the Church due to ignorance of the Scriptures. Thus the Catholic Church was established and the true Christians went underground, until at the time of the Reformation, they once again surfaced. This theory is often accompanied by a list of "inventions", or corruptions of both doctrine and practice, to which are assigned dates that generally post-date the Edict of 313.
The first problem with this theory is the fact that doctrines are mixed with practices. Doctrines are fixed beliefs (purgatory, papal infallibility, transubstantiation) and cannot change. Practices, on the other hand, are ways of doing things (the use of Latin, liturgical vestments, various prayers), and can and do change. The other problem with this theory is the fact that most of these reputed "inventions" occur years or even centuries before the Edict. A sacrificial priesthood, a hierarchy of bishops, prayers for the dead, veneration of Mary and the Saints, the Real Presence, papal authority and infallibility, the Sign of the Cross, and many more doctrines and practices are found in the Church Fathers long before the Edict. Furthermore, there is no record of an underground church resembling Protestantism existing at anytime before the Reformation, which would be very odd if such a church existed, because we have records of many heretical movements, probably every heretical group that ever existed, and among them, Protestantism is nowhere to be found.
Those who see the flaw in this argument claim that right after the conclusion of the apostolic age, the Church slowly departed from the truth until it became completely corrupt. Tertullian answered this charge around the year 200 (Prescription Against the Heretics, 20), by saying that Catholics of his day agreed on all points of doctrine, and it would be impossible for everyone to apostatize into the same false doctrines which all agreed to. Absent from the historical record is any objection to these doctrines, which certainly would have occurred if these were false doctrines. Asked to point to evidence of this apostasy, Protestants come up empty. The Catholic Church of today is consistent with the true church of the patristic age. Then, as now, they pointed to the succession of bishops to prove that they indeed were the true church. Protestantism, on the other hand, resembles the heresies. They had their origin in the teachings of one man, with doctrines that had no basis in tradition, and a church that resembled nothing existing before it.
Some Protestants, desperate to prove their church always existed, believe in what is called the "Trail of Blood" theory, which claims that a number of "heretical" churches (Montanists, Novatians, Donatists, Paulicians, Waldenses, Albigenses, Wycliffites, and Hussites) form an unbroken line of true Christians. The trouble with this is that these groups were either radically non-Christian (Montanists believed in two gods, Albigenses denied the incarnation) or too Catholic (Waldenses believed in the necessity of works for salvation), and disagreed with others, and with the Protestant churches today, either greatly or significantly.
Some Protestants go believe in the more outrageous claim that the Catholic Church borrowed her beliefs from ancient mystery religions. Such people resort to finding superficial similarities between Catholicism and pagan religions, and conclude that most things Catholic are pagan in origin. For instance, they say, both Catholics and Sun-god Baal worshipers had round wafers. But for one thing, the pagans used many shapes for their wafers, and secondly, the Jews offered wafers and cakes (Gen. 28:1-8; Ex. 29:1-2). Such similarities exist, but similarity does not imply descent. These pagan religions also resemble Protestantism in the things it and Catholicism have in common. Some pagan religions had a triune god (the Trinity) and claimed a deity was born of a virgin. In fact, some religions claimed to have a holy book that contained all religious truth (sola scriptura) and gave an assurance of salvation. To believe that these similarities are the result of borrowing is to commit the "after this, therefore because of this" fallacy. Sometimes there is no parallel. At times, there is no dependant relationship, the paganism and Catholicism developing similar practices independently of each other. Often enough, the Catholic practice is antecedent to the pagan practice. And sometimes, the Catholic practice has a pagan counterpart, but that counterpart was viewed negatively by the pagans.
However, it is true that some Catholic practices (images, the tonsure, processions) were borrowed from the pagans. What Protestants do not realize is that exchanging rings at weddings is also a pagan practice, and Protestants engage in this custom. Is there anything wrong with borrowing pagan practices? The fact is, most pagan practices, in and of themselves, are not evil (ie. burning candles and incense). The meaning we give these outward gestures make them legitimately Christian. It is true that the Catholic Church superimposed holy days on pagan feasts, but the pagan connections to them ceased and the holy day became thoroughly Christian. This was done in line with Paul's practice: "To the weak I became weak, so that I might win the weak. I have become all things to all people, that I might by all means save some" (1 Cor. 9:22; Acts 17). Circumcision (Jer. 9:25-26) and even baptism was used in many Eastern religions, long before the Jews and the Christians began the practices.
Along with its many errors, paganism had elements of truth. Christianity took what was good in these pagan religions, elements that could be used to enhance Christian worship, and removed all the pagan associations with them. They gave them all a new meaning, and therefore, replaced what was false with what was true. Rather than compromise with paganism, Christianity replaced it.