The kind of heresy which first stirred the Church to murderous repression was naturally that which struck at its monopolies. After the ancient schism of the Donatists, which so organized itself as to set up a rival Church, the sect which was most bloodily persecuted in the period of established Christianity from Theodosius onwards was the Manichæan, visibly the Church's most serious rival. So, in the Dark Ages, the heresies which roused most priestly anger were the movement against image-worship; the predestinarian doctrine of Gottschalk, which, though orthodox and Augustinian, was now felt to undermine the priest's power over souls in purgatory; and that which impugned the priestly miracle of the eucharist, the main hold of the priesthood over society. And the first resort to general and systematic massacre as against heresy in the West was made after there had arisen in the eleventh and twelfth centuries a movement of popular schism which assailed not only a number of leading rites and dogmas, but flatly denied the priestly prerogative.
Of this movement the first stages occurred in the eastern empire, in the sect known as Paulicians, who are first heard of under that name in Armenia in the seventh century. Their founder, however, one Constantine, afterwards known as Sylvanus, worked on existing bases. The name of the sect seems to have stood for an appeal to the teaching of Paul as against paganized Christianity; and it had Marcionite elements; but though it was at first anti-Gnostic and anti-Manichæan, it acquired both Gnostic and Manichæan or at least Mazdean characteristics, even in the teaching of Sylvanus. On the face of the case, it suggests both Persian and Moslem influences. Its practical heresies were opposition to the adoration of images and relics, to the use of the Old Testament, to the worship of saints, angels, and the Virgin, and to the prerogatives of monks and priests; the sectaries claiming to read the New Testament for themselves, in defiance of the virtual veto of the Greek Church on such study by the laity. For the rest, they insisted that baptism and the eucharist were spiritual and not bodily rites, and even reaffirmed the "Docetic" doctrine that Jesus had not a true human body, and so was incapable of suffering. Their flat denial of priestly claims marked them out as a specially obnoxious body, and they were fiercely persecuted, the founder being stoned to death.