Pope St. Callistus I

A former slave and convicted criminal sent to the Sardinian mines, Callistus was freed, became deacon under Pope Zephyrinus, and succeeded him as bishop of Rome. He was the first to teach that no sin is beyond the Church’s power to forgive — a doctrine that drew bitter opposition from the rigorist Hippolytus, but became the Church’s settled mind.

As deacon, Callistus oversaw the great Christian cemetery on the Appian Way that still bears his name — the Catacombs of San Callisto — where many early popes and martyrs were laid to rest. His pontificate, from about 217 to 222, was marked by courageous pastoral decisions that opened the doors of reconciliation to those who had fallen into grave sin.

Hippolytus set himself up as a rival bishop, making him the first antipope in history, yet Callistus refused to respond with condemnation, holding firm to the mercy he preached. He is believed to have been killed during a popular uprising in Trastevere, and tradition holds he was thrown into a well. His witness established that the Church is a hospital for sinners, not a museum of saints.