Bonosus , the founder of the sect of the Bonosiani, was bp. of Sardica in Illyria at the end of the 4th cent. (Tillemont, x. 754). Bonosus is only known to us as holding the same views with Helvidius with regard to the perpetual virginity of the mother of our Lord, and as to His brethren, whom he affirmed to have been the natural offspring of Joseph and Mary. At the synod of Capua, convened by Valentinian, a.d.391, to settle the rival claims of Flavian and Evagrius to the see of Antioch, opportunity was taken to lay an accusation against Bonosus. The synod was unwilling to consider the question, and transferred it to Anysius, the bp. of Thessalonica and metropolitan, and his suffragans, who, as a neighbour of Bonosus, might be supposed to be more fully acquainted with the merits of the case (Labbe, ii. 1033). Bonosus was condemned for heretical teaching, deposed, and his church closed against him. Bonosus consulted Ambrose, who recommended patience and submission. This prudent counsel was not followed, and the difference was exaggerated into a schism, which lasted into the 7th cent. Bonosus and his followers were widely accredited with heretical views respecting the conception and person of Christ. Mercator calls him an Ebionite, and a precursor of Nestorius (Dissert. i. de Haeres. Nestor. Â§ 6, ii. 315). But the Bonosians were more usually charged with Photinianism (Gennadius, de Eccl. Dogm. c. 52, "Photiniani qui nunc vocantur Bonosiaci"). Whether these charges were well grounded, or were based on the general unpopularity of the sect, it is impossible to determine. Their baptism was pronounced valid by the 17th canon of the second synod of Arles, a.d.445, on the ground that, like the Arians, they baptized in the name of the Trinity (Labbe, iv. 1013). But Gregory the Great, in a letter to the Irish bishops ( Ep. lib. ix. 61), includes them in those whose baptism the church rejected because the name of the Trinity was not invoked (cf. Gennadius, de Eccl. Dogm. , u.s. ). They on their part rebaptized those who joined them. The third council of Orleans, a.d.538, ordained that they who did so should be arrested by the royal officers and punished. The Bonosians were anathematized by pope Vigilius (Ep. xv.; Labbe, v. 333).