FAUSTINUS. - A Roman priest and follower of the schism of Ursicinus against Pope Damasus, by which he was forced to leave Rome, belonging to the sect of the Luciferians.
Of him we have: a *Libellus precum* or *De confessione verae fidei et ostentatione sacrae Communionis et persecutione adversantium veritati* (PL 13, 83-107), addressed, together with his fellow priest Marcellinus, from Eleutheropolis in Palestine, to the emperors Valentinian II, Theodosius, and Arcadius (c. 380 or 383), in which he earnestly implores imperial favor for the Luciferians, who were unworthily persecuted, violently accuses Pope Damasus and the Catholic bishops as usurpers, sacrilegious hypocrites, while praising the Luciferian bishops instead. Indeed, he must have gained the imperial court with this work, for Theodosius, through his praetorian prefect Cinegius (384), granted those holy and commendable bishops full liberty (PL 13, 107 ff.). At the instigation of Empress Flaccilla he had already written (c. 380) the *De Trinitate, sive de fide adversus arianos deducta*, in which he refutes the arguments of the Arians and defends the Catholic doctrine of the Holy Spirit (PL 13, 37-79); this is followed by a profession of faith: *Fides Theodosio oblata*. Both of these last writings are doctrinally orthodox.