Probably of Breton origin, he became a monk in the island monastery of Lérins and after about eight years succeeded Maximus as abbot. Conspicuous both as a meticulous observer of the rule and as an outstanding preacher, he succeeded Maximus as bishop of Riez in Provence c.460. Later he was expelled by Euric, an Arian Visigothic king. Faustus' theological work was sometimes controversial, not only for his denunciation of Arianism and Pelagianism, but also because he unwittingly adopted semi-Pelagian positions like those of Cassian. After Euric's death he returned to his diocese and to his commitment to pastoral work. After his death at the age of about ninety, he was deeply mourned and a large church was built in his honour. Various letters and sermons survive: the Roman Martyrology records his pastoral and theological importance. Feast: 28 September.
O.D.C.C. p. 601; B.L.S., ix. 261–2; Bibl. SS., v. 495–6. D.T.C., v. 2101–5.