Priscillian, the chief propagator of the doctrines professed by the sect known from his name as Priscillianists. They spread widely in Spain during the last third of the 4th century, and lingered there till the middle of the 5th century. The first seed of their doctrines is said to have been carried into Spain by a Memphian named Marcus, whose earliest disciples were Agape, a Spanish lady, and Helpidius, a rhetorician. Priscillian was a man of noble birth, pious and well educated; and his eloquence and nobility of character soon gathered round him a group of devoted followers, including two bishops, Instantius and Salvianus. From their hands he received episcopal ordination, and he established his see at Avila (Abila). Hyginus, bishop of Cordova, was the first to take alarm, but his measures were so gentle that he himself was covered with reproaches by the ultra-orthodox and fanatical. Priscillian's most determined enemies were Idacius, bishop of Emerita (Merida), and Ithacius, bishop of Sosuba. He was condemned and excommunicated at the synod of Saragossa (381), with three others of the leaders of the party. They next went to Rome to clear themselves before the pope, but were denied audience, and at Milan on the return journey they met as little sympathy from Ambrose. Under the vacillating rule of Gratian, however, they prospered, but their hopes were dashed to the ground by the usurpation of Clemens Maximus. From the judgment of the synod of Bordeaux (384) Priscillian appealed like Paul to Cæsar, and was at length summoned to appear at Treves. Martin of Tours was in favour of tolerant measures, but after his departure the fanatical party prevailed, and Priscillian, with others of the party, was condemned and put to death—the first who suffered death for heresy (385). Many Priscillianists recanted after the synod of Toledo (400), and soon after that of 447 they disappear altogether. Their doctrines contained Manichean and Gnostic elements, strange cosmical speculations based on primitive dualism, the doctrine of emanations and astrological fatalism. They practised rigid asceticism, and eschewed marriage and the use of animal food. One damning blot on their morals was that absolute veracity was only obligatory between themselves. Graver charges still were made against their morality; but it should be remembered that the only accounts we have are those of bitter enemies, and their principles, originally obscure enough, have been made darker by a cloud of calumny. 'If the Priscillianists violated the laws of nature,' says Gibbon, 'it was not by the licentiousness but by the severity of their lives.'
See Mansel's Gnostic Heresies and Neander's Church History; also Mandernach's Geschichte des Priscillianismus (Treves, 1851). Schepps claims to have discovered some of his writings; these he edited in vol. xviii. of the Corpus Scriptorum Ecclesiasticorum Latinorum (Vienna, 1888).