Lucifer of Cagliari (, ; died 20 May 370 or 371) was a bishop of Cagliari in Sardinia known for his passionate opposition to Arianism. He is venerated as a Saint in Sardinia, though his status remains controversial. Life Lucifer first appears in history as an envoy from Pope Liberius to the Emperor Constantius II, requesting the convening of a church council. At the Council of Milan in 355, he defended Athanasius of Alexandria against Arian attempts to secure his condemnation by Western bishops. It was reported that Constantius II, a supporter of Arian theology, confined Lucifer for three days in the Imperial Palace, where Lucifer continued to argue vehemently on behalf of Athanasius. Along with Eusebius of Vercelli and Dionysius of Milan, Lucifer was exiled for his opposition to the imperial ecclesiastical policy. He was banished first to Germanicia, the see of bishop Eudoxius, thereafter to Palestine and finally to the Thebais in Egypt. While in exile, he wrote fiery pamphlets to the Emperor in which he proclaimed himself to be ready to suffer martyrdom for his beliefs. Disciple of St Eusebius of Rome, he became a scholar in Greek and Hebrew languages, and then was baptized by the Pope Eusebius. St Lucifer wrote a well documented Vita S. Eusebii Vercellensis (from Latin, "Life of Saint Eusebius of Vercelli"). After the death of Constantius and the accession of Julian the Apostate, Lucifer and other expatriated bishops were allowed to return from exile in 361 or 362. However, he would not be reconciled to former Arians.He opposed the Bishop Meletius, who came to accept the Nicene creed (and for that was driven out by Arians). Although Meletius had the support of many proponents of Nicene theology at Antioch, Lucifer put his support behind the Eustathian party which had unflinchingly stood by the Nicene creed, and prolonged the schism between Meletians and Eustathians by consecrating without licence a Eustathian, Paulinus, as bishop. He subsequently returned to Cagliari where, according to Jerome, he died in 370. He may have been excommunicated as is hinted in the writings of Ambrose of Milan and Augustine of Hippo, as well as Jerome, who refers to his followers as Luciferians. There is extant a work known as Libellus precum ad Imperatores, written by two Luciferian clergy called Faustinus and . Jerome discusses Lucifer and his supporters in his polemic Altercatio Luciferiani et orthodoxi ("Altercation of a