Cornelius was a Roman of senatorial rank, elected pope after a fourteen-month vacancy following the Decian persecution. His brief two-year pontificate was dominated by the lapsi controversy — what to do with Christians who had sacrificed under threat of death and now wanted readmission to the Church. Cornelius, supported by Cyprian of Carthage, took the moderate position that they could be readmitted after appropriate penance.
The rigorist antipope Novatian refused all reconciliation; the schism he founded survived for centuries. Cornelius's correspondence with Cyprian — preserved as part of Cyprian's collected letters — is the principal source for both their pontificates.
Exiled by the new Emperor Gallus in 252, Cornelius died in his exile at Centumcellae (Civitavecchia) in June 253. The Catacomb of San Callisto contains the great inscribed tomb that for two centuries was the most magnificent in Christian Rome; his name appears in the Roman Canon of the Mass with Cyprian's.