[1] Marcellinus' pontificate began at a time when Diocletian was Roman emperor, but had not yet started to persecute the Christians, and their membership grew.

In the beginning of the 5th century, Petilianus, the Donatist bishop of Cirta, says that Marcellinus and his priests had given up the holy books to the pagans during the persecution and offered incense to false gods.

[1][2] The records of the pseudo-Council of Sinuessa, which were fabricated at the beginning of the 6th century, state that Marcellinus after his fall presented himself before a council, which refused to try him on the ground that prima sedes a nemine iudicatur ("The first See is judged by none").

[2] According to the Liber Pontificalis, Marcellinus was buried on 26 April 304 in the cemetery of Priscilla, on the Via Salaria, 25 days after his martyrdom; the Liberian Catalogue gives as the date 25 October.

[2] Marcellinus was mentioned in the General Roman Calendar, into which a feast day in his honour jointly with that of Saint Cletus on 26 April was inserted in the thirteenth century.