Puritanism, millenarianism, mysticism and rationalism: the four permanent sources of heresy. None of them are necessarily heretical, nor need they be radical. But at certain times and at certain places something has happened to swell these streams of thought into a flood, menacing the entire structure of Church and society. One of these floods occurred in the twelfth and thirteenth centuries in Western Europe; another during the Reformation and the religious wars of the sixteenth and seventeenth centuries. By studying these periods we may come to some conclusions about the significance of heresy and its contribution to society.
The remarkable thing about the twelfth and thirteenth century outburst of heresy was its universality. In the Byzantine Empire there had been some spectacular heresies. Government had been convulsed, archbishops had hurled anathemas at each other, and armies of barbarous monks had been thrown into action to decide between the single and dual nature of Christ. But these recondite heresies, more often than not, had been slogans in the long struggle for power between the churches of Constantinople and Alexandria. The really important heresies- the permanent heresies which had their root in the Bible and in society would recur again and again- had risen sporadically: the Donatists in fourth century Africa, the Paulicians in seventh century Armenia, iconoclasm in eighth-century Constantinople.
But now a whole crop of such heresies occurred at one time, and all over Christendom. In Lyons, a rich merchant, Peter Waldo, gathered a congregation of Waldenes, or Poor Men of Lyons, and preached a crusade to restore the Law of Christ. In Lombardy, a Puritan sect, the Umiliati, similarly preached and practiced the evangelical virtues; in Umbria, Francis of Assisi created the Cult of Holy Poverty; in France, Germany and Italy, Arnold of Brecia, a pupil of the learned Abelard, denounced the temporal power of the pope; and in Paris, in 1209, a prophet was burned for declaring the pope to be Antichrist.
Meanwhile in southern France, the most ascetic, most highly organized of all heretics, the Albigenses, openly challenged the Church by setting up a rival organization. They had their own clergy, the perfecti, and their own laity, the credentes; they had their own theology, based on Manichaean dualism, which refused any compromise with the forces of evil, and among the forces of evil they numbered, especially, the established church of Rome.