The fourth century brought about a great change in the condition of the Church, especially in the City of Rome. For the last twenty years of the third century the Christians had enjoyed a comparative rest from persecution. Great numbers were converted, but numbers do not always imply fervor, and there were many complaints that the charity of the Christians was growing cold. In the year 303, how r ever, the Emperor Diocletian was persuaded to undertake the task of extirpating the Church. This was the last of the Ten Persecutions, and it was also the bloodiest. The storm raged for some ten years, and was ended when the Edict of Milan, in 313, gave toleration to the Christian religion. With the conversion of Constantine came triumph, and, with the exception of the brief reign of Julian the Apostate, the Roman empire was a Christian state. The first effect of this change was that multitudes poured into the Church, and the tendency to laxness marked at the end of the third century was renewed, and we no longer have to deal with a small community composed of fervent souls, tempered in the fires of adversity, but with a mixed multitude, many of whom were Christian only in name.
One of the first efforts of this change in the complexion of the Christian body was the rise of Monasticism. In No. 65 you will find an explanation of the word. The movement was a reaction from the growing worldliness of the Christian community at the end of the third century, and its effects on the Liturgy are chiefly to be found in this, that the monks had all their time to give to prayer, so that much of the strain was taken off the Mass and distributed through other services. In consequence, we find the time occupied by the Sacrifice considerably shortened a result to which the character of the new converts also contributed.
On the other hand, the rush of imperfectly instructed pagans into the Church gave an impetus to the heresies that had existed in the Church from the beginning, because, as the Parable tells us, the tares and the wheat grow together until the harvest. The Catholic religion is a revealed religion. That is to say, it consists of truths made known by God. The teaching of those truths is given into the hands of a society known as the Church. They are all connected one with the other, so that, if one is rejected, the rest are soon rejected also. Many of them are hard to understand. Men try to explain them as best they can. Sometimes they succeed in casting light upon them; at other times they explain them away altogether. To the latter class belong the heretics. "Heresy" is a Greek word which means to "pick" and "choose." The essence of heresy consists in this, that men will not con sent to be taught by the Church, but will insist on picking and choosing their belief. They will hold to what pleases them and they will reject what they do not like. While the Church was persecuted, it is true there were heresies, but those heresies were few and insignificant. Men who took their lives in their hands because of their faith in Christ were not likely to whittle down and explain away that faith. But, when the conversion of Constantine brought men of a different caliber into the Church, heresies became many and powerful. The first, which was founded by Arius, an Alexandrian, struck at the mystery of the Holy Trinity. Like the Unitarians of today, he denied that Jesus was God, equal to the Father in all things. This heresy spread very rapidly, but was condemned by the Church at the first Council of Nice, in 325. At this Council was drawn up the famous Nicene Creed or formula of belief. Though condemned, the Arians continued to propagate their doctrines, and, during the fifty years succeeding the Council of Nice, they kept the Church in continual turmoil. A heresy similar to that of Arianism was condemned in 381 at the Council of Constantinople. That heresy denied that the Holy Ghost was God. An addition was made to the Nicene Creed affirming the Godhead of the Third Person of the Blessed Trinity. The following century saw the rise of the Pelagian heresy, which denied the necessity of Grace. The heresy of Nestorius asserted that there were two persons in Christ, the divine and the human. Therefore the Blessed Virgin, being the mother of the human person only, was the mother of Christ, but not the mother of God. In the year 431 the Council of Ephesus condemned this heresy, and taught that there was only one person in Jesus Christ, and that the Blessed Virgin should be called the mother of God, because the same Person who is the Son of God is also the Son of the Virgin Mary. A heresy the very opposite of this was condemned at Chalcedon in 451. It held that, as there was only one person in Christ, so there was only one nature, and therefore He was not properly man. A religious sect, sometimes called a heresy, but in reality a distinct religion, had been very active in the third and fourth centuries. It originated in Persia, and was known as Manichaeism. This system taught that there were two gods, a good god and an evil god. The evil god created the world, and therefore everything pertaining to the world was evil. The object of religion was to free the spirit from the burden of the flesh. The "perfect," as they were called, or the members of the inner circle of Manichaeism, were forbidden the use of animal food and intoxicating liquors. They were not permitted to kill animals, to injure vegetable life, to labor with their hands, or to get married.
- taken from The Mass, by Father Peter Christopher Yorke