Opposition to Arianism
The defining note of Victorinus in the tradition is his firm stand against Arianism. Arianism, which held that the Son was a created being subordinate to the Father, had persisted among the Germanic peoples who entered Italy, and the Lombard kingdom of the seventh century counted many Arians among its ranks. As bishop of Como, Victorinus is remembered for upholding the orthodox confession of the full divinity of Christ against this teaching.
The sources do not preserve the particulars of his struggle — no record of councils attended, writings composed, or confrontations endured survives in the brief accounts. He appears to have died of natural causes rather than as a martyr.