Marcellus was elected pope in the year 308, when the early Church was combating the effects of the devastating persecution under Emperor Diocletian. Pope Marcellus received back into the Church those apostates who gave indications of repentance for having denied the Christian Faith during the reign of terror. A group revolted against the Papal penances imposed upon them and used their influence with Emperor Maxentius to have the Pope exiled from Rome. Pope Marcellus died during the first year of his banishment, safeguarding the integrity of Church discipline even at the sacrifice of his own freedom and life.
We beg Thee, O Lord, through the gifts which we have offered, in Thy kindness enlighten Thy Church, so that everywhere Thy flock may prosper and her Shepherds by Thy guidance be pleasing to Thy name. Through our Lord . . .
Multiply in Thy Church, we beseech Thee, O Lord, the spirit of grace which Thou hast bestowed, so that, by the prayers of blessed Marcellus Thy Martyr and Supreme Pontiff, neither shall the flock be lacking in obedience to the Shepherd nor the Shepherd be lacking in watchfulness over the flock. Through our Lord . . .