Saint Cornelius was Pope for a scant two years in the middle of the third century, elected in 251 and put to death in 253 in the persecution under Emperor Decius. During his short tenure, he had to deal with the machinations of his fellow bishop Novatian, who eventually declared himself the true Pope, thus also unwittingly making himself history’s first anti-Pope. Novatian was an early rigorist, teaching that certain sins were so evil, to beyond the pale – especially apostasy, failing in the face of martyrdom, sacrificing to the ‘gods’ even under pretense – that one could never again seek reconciliation with the Church (nor with God, one might presume). Banished! Cast off! Into the outer darkness! Anathema sit!
Cornelius, on the other hand, inspired by the Holy Spirit offered by the grace of his office, realized that God’s mercy was far greater than any of our sins, and that if men must forgive each other ‘seventy times seven times’, God forgiveness is infinitely beyond this, even welcoming back apostates, and those who may have apostatized seven times.
Novation proved implacable and obstinate, so was excommunicated along with his followers in a synod called by the Pope. But Cornelius, we may presume, would have welcomed them back in, had they too repented.