Lucifer of Cagliari (LUCIFER CALARITANUS), bishop, must have been born in the early years of the fourth century; d. in 371. His birthplace and the circumstances of his youth are unknown. He first appears in ecclesiastical history, in full maturity of strength and abilities, in 354 when he was deputed by Pope Liberius, with the priest Pancratius and the deacon Hilary, to request the Emperor Constantius to convene a council, to deal with the accusations directed against St. Athanasius and his previous condemnation. This council was convened at Milan. Lucifer there defended the Bishop of Alexandria with much passion and in very violent language, thus furnishing the adversaries of the great Alexandrian with a pretext for resentment and further violence, and causing a new condemnation of Athanasius. Constantius, unaccustomed to independence on the part of the bishops, grievously maltreated Lucifer and his colleague, Eusebius of Vercelli. Both were exiled, Lucifer being sent to Germanica, in Syria, and thence to Eleutheropolis in Palestine; he was finally relegated to the Thebaid.
In the course of this exile Lucifer wrote an extremely virulent pamphlet entitled “Ad Constantium Augustum pro sancto Athanasio libri II”, an eloquent defense of Catholic orthodoxy, but in such exaggerated language that it overshot the mark and injured the cause it was meant to serve. Lucifer boasted of his work, and Constantius, tyrant that he was, refrained from further revenge. After the death of Constantius, Julian allowed all the exiles to return to their cities. Lucifer went to Antioch, and at once meddled in the dissensions which divided the Catholic party. He prolonged and embittered them by consecrating a bishop who appeared to him capable of continuing the opposition to the bishop and party which he judged the weaker under the circumstances. Incapable of tact, he aggravated the dissenters, instead of dealing cautiously with them in order to win them, and displayed special severity towards those Catholics who had wavered in their adherence to the Nicene Creed. About this time a Council of Alexandria presided over by St. Athanasius decreed that Arians renouncing their heresy should be pardoned and that bishops who, by compulsion, had temporized with heretics should not be disturbed. Against this indulgence Lucifer protested, and went so far as to anathematize his former friend, Eusebius of Vercelli, who carried out the decrees of the Council of Alexandria. Seeing that his extreme opinions won partisans neither West nor East, he withdrew to Sardinia, resumed his see, and formed a small sect called the Luciferians. These sectaries pretended that all priests who had participated in Arianism should be deprived of their dignity, and that bishops who recognized the rights of even repentant heretics should be excommunicated. The Luciferians, being earnestly opposed, commissioned two priests, Marcellinus and Faustinus, to present a petition, the well-known “Libellus precum”, to the Emperor Theodosius, explaining their grievances and claiming protection. The emperor forbade further pursuit of them, and their schism seems not to have lasted beyond this first generation.