Bishop of Cagliari, and founder of the Luciferians, first appears in history as a zealous antagonist of Arianism. In 354 he was deputed by Liberius, Bishop of Rome, to advocate the cause of Athanasius at the council of Milan, an office which he discharged with such persistent boldness, that he and his fellow-legate, Eusebius of Vercelli, were banished by the Arian emperor, Constantine. After his place of exile had been changed several times without producing any corresponding alleviation of his sufferings, he settled down at Eleutheropolis, in Syria, and there wrote his chief work, Ad Constantium Augustum pro Sancto Athanasio, Libri II. The unbridled invective and outrageous vehemence of this book were not more remarkable than the boldness of Lucifer in avowing the authorship, when afterwards interrogated by the emperor. Soon after this Lucifer seems to have been removed to Egypt. On his release from exile at the death of Constantius, the council of Alexandria commissioned him, along with Eusebius, to heal the division in the church of Antioch that had arisen from the supposed Arianism of Meletius, bishop of that see. Instead, however, of fulfilling his duty, he widened the schism by attempting to place Paulinus in the bishopric, and thus laid himself open to a reproof from Eusebius and his other long-tried friends. Chafing under the rebuke of all sections of the church, and displeased with the decree of the Alexandrian council for readmitting into ecclesiastical communion those bishops who had temporized with the Arians, Lucifer withdrew, in 363, to his native island of Sardinia, and there founded the small sect known by his name. He died about A.D. 370. Besides the book mentioned above, his other works are—Epistola ad Eusebium; De non Conveniendo cum Haeretici; De Regibus Apostolicis; De non Parcendo in Deum delinquentibus; Mortendum pro Filio Dei; Epistola ad Florentium Magistrum Officiores; and Epistola ad Catholicos. The last is not extant. Deficient in method and argument, and pervaded by an acrimonious and intolerant spirit, these works merit preservation solely in virtue of the many scriptural quotations which they contain. They were first collected and published by John du Tillot, Bishop of Meaux, Paris, 8vo, 1568, and afterwards reprinted in the Magna Bibliotheca Patrum, 1618, and in the Bibliotheca Patrum of Galland, folio, Venice, 1770. The best edition is that of the Brothers Coleti, folio, Venice, 1778.

The Luciferians (who did not long outlive their founder) disowned all who had ever been tainted with Arianism and all who countenanced those who had been reclaimed from that creed. They renounced, accordingly, all the Christian world beyond their own confined pale. Augustine supposes that they also held that the soul, like the carnal nature, was transmitted from parent to child.