His heresy was based on the irregular teaching on the St. Mother of God, preached by Fotin, the bishop of Sirmium (Sremska Mitrovica), who had denied the virginity of the Mother of God. At the Council of Capua in 391, his preaching was rejected and the religious service performed by the priests ordained by the heretic Bonosus, the bishop of the town of Niš, was pointed out. The bishop of Remesiana (Bela Palanka) Nicetas came to Niš in 392, in order to dissuade Bonosus from the wrong teachings on the St. Mother of God. Bonosus is also mentioned in the letters of the Pope Innocent I, addressed to his successor Marcianus, the bishop of Niš, dated 409 and 414, from which it can be concluded that Bonosus was still alive. His attitudes represent the last reverberation of Arius' teaching throughout the region of Illyricum that was rejected 391 at the Council of Capua. The novel of the Emperor Justinian I confirms that Bonosus' heresy survived up to his times.