Lucifer was Bishop of Cagliari in Sardinia. At the synod of Arles, a.d. 353, he had strenuously resisted the condemnation of St. Athanasius, though it was urged by the Emperor Constantius, maintaining that the Nicene faith was opposed in the person of Athanasius. Against the synod of Milan, a.d. 355, he was equally resolute in defence of the belief of Nicæa, for which the emperor banished him to Syria. But when the synod of Alexandria, a.d. 362, determined on the restoration of certain Arians after repentance, he withdrew from Catholic Communion.