Theonestus of Altinum

Theonestus of Altinum (Theonestos) was, according to tradition, bishop of Philippi in Macedonia, driven from his diocese by the Arians. He made a pilgrimage to Rome, then went to Milan and received a martyr's death at Altinum, north-⁠east of Venice, on 30 October 425 according to the German source, an uncertain time. His cult is lively above all in the cities of northern Italy; around 710 he is attested as patron of a monastery in Treviso.

The account of his passion is lost. A monk of the monastery of Saint Alban in Mainz seems to have known it, around 800, and identified him with Bishop Theonastus of Mainz; according to the Mainz tradition, he was stoned, and from this comes the legend of Theonestus on the middle Rhine. His commemoration is on 30 October, in the Western calendar (new style). A holy martyr of the undivided Church, venerated in the West.