According to his worthlessm "acts", he was a native of Pampeluna, in Navarre, initiated in the Christian faith by St. Honestus, a disciple of St. Saturninus of Toulouse, and consecrated bishop of Toulouse by St. Honoratus to preach the gospel in the remoter parts of Gaul. Being arrived at Amiens, Firminus there chose his residence and founded a church of faithful disciples. He received the crown of martyrdom in that city, where the bishop St. Firminus II (who is honoured on September 1) built a church over his tomb, dedicated under the invocation of the Blessed Virgin, but now known as St. Acheul's. It is possible that Firminus I and Firminus II were only one man; they are both unheard of before the ninth century, the first known bishop of Amiens being Eulogius in the middle of the fourth century. Firminus was probably simply a missionary bishop in Gaul.
Two texts are known which claim to represent the "acts" of St. Firminus. The Bollandists (September, vol. vii) print one entire with extracts from the other. See also C. Salmon, Histoire de S. Firmin (1861), and Duchesne, Fastes Épiscopaux, vol. iii, pp. 122-127. For Firminus II, see Duchesne, loc. cit.; the Acta Sanctorum, September, vol. i. For both a popular account is provided by J. Corblet, Hagiographie du diocèse d' Amiens (1870), vol. ii, pp. 31-216.
Butler's Lives of The Saints, Herbert J. Thurston, S.J. and Donald Attwater
Nihil Obstat: PATRICIVS MORRIS, S.T.D., L.S.S., CENSOR DEPVTATVS.
Imprimatur: E. MORROGH BERNARD, VICARIVS GENERALIS
WESTMONASTERII: DIE XXIII FEBRVARII MCMLIII