Having robbed his master and being obliged to fly, he providentially met with St. Paul, then a prisoner for the faith at Rome, who there converted and baptized him, and sent him with his canonical letter of recommendation to Philemon, by whom he was pardoned, set at liberty, and sent back to his spiritual father, whom he afterwards faithfully served.
That apostle made him, with Tychicus, the bearer of his Epistle to the Colossians, and afterwards, as St. Jerome and other Fathers witness, a preacher of the Gospel and a bishop.
He was crowned with martyrdom under Domitian in the year 95.
Feast Day of Saint Onesimus
The Feast Day of Saint Onesimus is February 16. The origin of Feast Days: most saints have specially designated feast days and are associated with a specific day of the year and these are referred to as the saint's feast day.
The feast days first arose from the very early Christian custom of the annual commemoration of martyrs on the dates of their deaths at the same time celebrating their birth into heaven.