We know the beliefs of the Cathars, or "Albigensians" mainly through the writings of opponents. This account is from an early thirtheenth century chronicle
First it is to be known that the heretics held that there are two Creators; viz. one of invisible things, whom they called the benevolent God, and another of visible things, whom they named the malevolent God. The New Testament they attributed to the benevolent God; but the Old Testament to the malevolent God, and rejected it altogether, except certain authorities which are inserted in the New Testament from the Old; which, out of reverence to the New Testament, they esteemed worthy of reception. They charged the author of the Old Testament with falsehood, because the Creator said, "In the day that ye eat of the tree of the knowledge of good and evil ye shall die;" nor (as they say) after eating did they die; when, in fact, after the eating the forbidden fruit they were subjected to the misery of death. They also call him a homicide, as well because he burned up Sodom and Gomorrah, and destroyed the world by the waters of the deluge, as because he overwhelmed Pharaoh, and the Egyptians, in the sea. They affirmed also, that all the fathers of the Old Testament were damned; that John the Baptist was one of the greater demons. They said also, in their secret doctrine, (in secreto suo) that that Christ who was born in the visible, and terrestrial Bethlehem, and crucified in Jerusalem, was a bad man, and that Mary Magdalene was his concubine; and that she was the woman taken in adultery, of whom we read in the gospel. For the good Christ, as they said, never ate, nor drank, nor took upon him true flesh, nor ever was in this world, except spiritually in the body of Paul....
They said that almost all the Church of Rome was a den of thieves; and that it was the harlot of which we read in the Apocalypse. They so far annulled the sacraments of the Church, as publicly to teach that the water of holy Baptism was just the same as river water, and that the Host of the most holy body of Christ did not differ from common bread; instilling into the ears of the simple this blasphemy, that the body of Christ, even though it had been as great as the Alps, would have been long ago consumed, and annihilated by those who had eaten of it. Confirmation and Confession, they considered as altogether vain and frivolous. They preached that Holy Matrimony was meretricious, and that none could be saved in it, if they should beget children. Denying also the Resurrection of the flesh, they invented some unheard of notions, saying, that our souls are those of angelic spirits who, being cast down from heaven by the apostacy of pride, left their glorified bodies in the air; and that these souls themselves, after successively inhabiting seven terrene bodies, of one sort or another, having at length fulfilled their penance, return to those deserted bodies.
It is also to be known that some among the heretics were called perfect" or "good men;" others "believers" of the heretics. Those who were called perfect, wore a black dress, falsely pretended to chastity, abhorred the eating of flesh, eggs and cheese, wished to appear not liars, when they were continually telling lies, chiefly respecting God. They said also that they ought not on any account to swear.
Those were called "believers" of the heretics, who lived after the manner of the world, and who though they did not attain so far as to imitate the life of the perfect, nevertheless hoped to be saved in their faith; and though they differed as to their mode of life, they were one with them in belief and unbelief Those who were called believers of the heretics were given to usury, rapine, homicide, lust, perjury and every vice; and they, in fact, sinned with more security, and less restraint, because they believed that without restitution, without confession and penance, they should be saved, if only, when on the point of death, they could say a Pater noster, and received imposition of hands from the teachers.
As to the perfect heretics however they had a magistracy whom they called Deacons and Bishops, without the imposition of whose hands, at the time of his death, none of the believers thought that he could be saved; but if they laid their hands upon any dying man, however wicked, if he could only say a Pater noster, they considered him to be saved, that without any satisfaction, and without any other aid, he immediately took wing to heaven.