Priscillian (died 385) was bishop of Ávila and a theologian from Roman Gallaecia (in the Iberian Peninsula), the first person in the history of Christianity to be executed for heresy (though the civil charges were for the practice of magic). He founded an ascetic group that, in spite of persecution, continued to subsist in Hispania and Gaul until the later 6th century. Tractates by Priscillian and close followers, which had seemed certainly lost, were recovered in 1885 and published in 1889.
Priscillian's career 
The principal and almost contemporary source for the career of Priscillian is the Gallic chronicler Sulpicius Severus, who characterized him (Chronica II.46) as noble and rich, a layman who had devoted his life to study, vain of his classical pagan education, already being looked on with misgivings (see Gregory of Tours). He was an ascetic mystic and regarded the Christian life as continual intercourse with God. His favourite idea was Saint Paul`s "Know ye not that ye are the temple of God?" (I Corinthians 6:19) and he argued that to make himself a fit habitation for the divine a man must, besides holding the Catholic faith and doing works of love, renounce marriage and earthly honour, and practise a hard asceticism. It was on the question of continence in, if not renunciation of, marriage, that he came into conflict with the authorities, and his influence among growing numbers of followers threatened the authority of the church when the bishops Instantius and Salvian were won over by his eloquence and his severely ascetic example.
His notable opponents in Hispania were Hyginus, bishop of Cordoba, and Hydatius, bishop of Mérida. Their complaint to Pope Damasus I (also from Hispania) resulted in a synod held at Zaragoza in 380, in the absence of Priscillian or any of his followers. The canons issued by the synod shed light on Priscillian's practices, by condemnation. That is, much of what was forbidden was condemned because the Priscillianists were practicing it. The council held the following: women were forbidden to join with men during the time of prayer; fasting on Sunday was condemned; no one was to retreat at home or in the mountains during Lent; the Eucharist was to be taken in church and not brought home; excommunicated persons were not to be sheltered by bishops; a cleric was forbidden to become a monk on the motivation of a more perfect life; no one was to assume the title "doctor" (Latin for teacher); women were not to be accounted "virgins" until they had reached the age of forty.
Through the exertions of Hydatius of Emerita, the leading Priscillianists, who had failed to appear before the synod of Hispanic and Aquitanian bishops to which they had been summoned, were excommunicated at Zaragoza in October 380, according to Sulpicius, a conclusion that was emphatically denied in a letter to Damasus, Liber ad Damasum episcopum (McKenna, note 14).
Among the more prominent of Priscillian's friends were two bishops, Instantius and Salvianus; Hyginus of Cordova also joined the party. After a Priscillianist delegation to Hydatius was turned away, they appointed Priscillian bishop of Ávila, and the orthodox party found it necessary to appeal to the emperor Gratianus, who issued an edict threatening the sectarian leaders with banishment. Consequently, the three bishops, Instantius, Salvianus and Priscillian, went in person to Rome, to present their case before Damasus. But neither the Pope nor Ambrose, bishop of Milan, granted them an audience. Salvianus died in Rome, but through the intervention of Macedonius, the imperial magister officiorum and an enemy of Ambrose, they succeeded in procuring the withdrawal of Gratianus' edict, and the attempted arrest of Ithacius of Ossonuba.
On the murder of Emperor Gratianus in Lyon and the accession, at Trier (Trèves, in Germany) at least, of the usurper Magnus Maximus (383), Ithacius fled to Trier, and in consequence of his representations a new synod was held (384) at Bordeaux, where Instantius was deposed. Priscillian appealed to the Emperor, with the unexpected result that, with six of his companions, he was beheaded at Trier in 385, the first Christian heretics to be put to death by Christians. This act had the approval of the synod which met at Trier in the same year, but Ambrose of Milan, Pope Siricius and Martin of Tours protested against Priscillian's execution, largely on the jurisdictional grounds that an ecclesiastical case should not be decided by a civil tribunal, and worked to reduce the persecution.
Priscillian's contemporary following 
Priscillian and his sympathizers included many women, who were welcomed as equals of men. They were organised into bands of spirituales and abstinentes. This insistence on celibacy explains the charge of Manichaeism some levelled against Priscillian (even Jerome, for his talk of the sordes nuptiarum, had been similarly accused, and to escape popular indignation had retired to Bethlehem). To this charge was added the accusation of magic and licentious orgies (a particularly preposterous charge, given the nature of Priscillian's doctrines). Latronianus, executed with Priscillian at Trier, was noted as a poet worthy of the ancients by Jerome.
Continued Priscillianism 
The heresy, notwithstanding the severe measures taken against it, continued to spread in Gaul as well as in Hispania; in 412 Lazarus, bishop of Aix-en-Provence, and Herod, bishop of Arles, were expelled from their sees on a charge of Manichaeism. Proculus, the metropolitan of Marseille, and the metropolitans of Vienne and Narbonensis Secunda were also followers of the rigorist tradition for which Priscillian had died.
Something was done for its repression by a synod held by Turibius of Astorga in 446, and by that of Toledo in 447; as an openly professed creed it had to be declared heretical once more by the second synod of Braga in 563, a sign that Priscillianist asceticism was still strong long after his execution. "The official church," says F. C. Conybeare, "had to respect the ascetic spirit to the extent of enjoining celibacy upon its priests, and of recognizing, or rather immuring, such of the laity as desired to live out the old ascetic ideal. But the official teaching of Rome would not allow it to be the ideal and duty of every Christian. Priscillian perished for insisting that it was such".
The long prevalent estimation of Priscillian as a heretic and Manichaean rested upon Augustine, Turibius of Astorga, Leo the Great and Orosius (who quotes a fragment of a letter of Priscillian's), although at the Council of Toledo in 400, fifteen years after Priscillian's death, when his case was reviewed, the most serious charge that could be brought was the error of language involved in a misrendering of the word innascibilis ("unbegettable").
It is not always easy to separate the genuine assertions of Priscillian himself from those ascribed to him by his enemies, nor from the later developments taken by groups who were labelled Priscillianist. Priscillian casts a long shadow in the north of Hispania and the south of Gaul, where mystic asceticism has repeatedly been carried to extremes that the political mainstream has denounced as heretical.
Priscillian was long honored as a martyr, not heretic, especially in Gallaecia (modern Galicia and northern Portugal), where his body was reverentially returned from Trier. Some claim that the remains found in the 8th century at the site rededicated to Saint James the Great— Santiago de Compostela— which even today are a place of pilgrimage, belong not to the apostle James but to Priscillian.
Writings and rediscovery 
Some writings by Priscillian were accounted orthodox and were not burned. For instance he divided the Pauline epistles (including the Epistle to the Hebrews) into a series of texts on their theological points and wrote an introduction to each section. These canons survived in a form edited by Peregrinus. They contain a strong call to a life of personal piety and asceticism, including celibacy and abstinence from meat and wine. The charismatic gifts of all believers are equally affirmed. Study of scripture is urged. Priscillian placed considerable weight on apocryphal books, not as being inspired but as helpful in discerning truth and error. It was long thought that all the writings of the heretic himself had perished, but in 1885, Georg Schepss discovered at the University of Würzburg eleven genuine tracts, published in the Vienna Corpus 1886. Though they bear Priscillian's name, four describing Priscillian's trial appear to have been written by a close follower.
According to Raymond Brown's introduction of his edition Epistle of John, the source of the Comma Johanneum, a brief interpolation in the First Epistle of John, known since the fourth century, appears to be the Latin Liber Apologeticus by Priscillian.
The modern assessment of Priscillian is summed up in Cambridge professor Henry Chadwick's Priscillian of Avila: The Occult and the Charismatic in the Early Church, (Oxford University Press) 1975.
See also 
Further Reading 
Fletcher, Richard A., St. James' Catapult: The Life and Times of Diego Gelmirez, Chapter 1 and passim: Galicia, which offers a historical and geographical background to the building of the cathedral in Compostela, and
Burrus, Virginia, The Making of a Heretic: Gender, Authority, and the Priscillianist Controversy, U. of California Press, 1995.
McKenna, Stephen, "Priscillianism and Pagan Survivals in Spain" in Paganism and Pagan Survivals in Spain up to the Fall of the Visigothic Kingdom. The present account depends on this thoroughly cited chapter.
Saunders, Tracy, Pilgrimage to Heresy (iUniverse, 2007) - in Spanish: Peregrinos de la Herejía (Bóveda 2009) - offers a fictionalised version of the events in Priscillian's story and furthers the suggestion put forth by Prof. Henry Chadwick that Priscillian may be the occupant in the tomb in Santiago de Compostela
- "Catholic Encyclopedia". Newadvent.org. 1911-06-01. Retrieved 2012-03-07.
- This entry adapts some information originally from the 1911 Encyclopædia Britannica.