Nazarius was a citizen of Rome whose father was Jewish or pagan. His mother was Saint Perpetua. Nazarius was a student of Saint Peter and was baptized by Saint Linus. During the persecutions of Nero, Nazarius fled Rome and preached in Lombardy, visiting Piacenza and Milan, where he met the brothers Gervase and Protase, who had been imprisoned and who inspired Nazarius by their example.
Nazarius was whipped and condemned to exile by the authorities. He traveled to Gaul, where a young boy of nine, Celsus, was entrusted to his care after the boy’s mother asked Nazarius to teach and baptize her son. Nazarius raised him as a Christian. The two were arrested, tortured, and imprisoned for their faith. They were released on condition they would not preach at this place any longer. They preached in the Alps and built a chapel at Embrun, and then continued on to Geneva, and then Trier. They preached in Trier, and converted many to Christianity, and they were imprisoned once again there. Celsus was entrusted to the care of a pagan lady, who attempted to make him abjure his faith. Celsus refused, and was eventually returned to Nazarius.
An additional legend that describes their time at Trier states that they were tried by Nero there, who ordered the two saints to be drowned. Nazarius and Celsus were taken in a ship and thrown overboard, but a storm suddenly arose, frightening the sailors. The sailors pulled the two saints back on board.
The two saints left Trier and reached Genoa, and then returned to Milan, and were arrested again. They refused to sacrifice to the Roman gods, and were beheaded.