Pope Cornelius was the 21st pope of the Roman Catholic Church, serving from around 251 to 253 AD. He is known for his leadership during a time of persecution against Christians under the Roman Emperor Decius. Cornelius emphasized the importance of reconciliation for those who had lapsed in their faith during these difficult times. His papacy was marked by a significant conflict with the antipope Novatian, who advocated a stricter approach to penance. Cornelius supported a more lenient stance, allowing lapsed Christians to return to the Church after genuine repentance. He was later recognized as a martyr and is commemorated on September 16.