St Callistus I was the 16th Pope from 217 to 222. He had been one of the Christians sentenced to work in the mines of Sardinia. Later he was freed when Pope Victor I visited the mines with a list of those to be released and while his name was not on it Callistus pleaded and convinced Victor to take him also. The mines had greatly diminished the health of Callistus and he was sent to Antium to recuperate while he collected a allowance from Pope Victor I. When Pope Zephyrinus started as the Roman See he called Callistus to Rome and made him a deacon while entrusting him to oversee the burial chambers of the Church along Appian Way.
When he was chosen to succeed Zephyrinus it sparked a schism when Hippolytus led the followers of his theological school out of the Church and declared himself a rival or anti-pope. Callistus was the first of four Popes to serve while Hippolytus stood in opposition. One issue that was decried by both Hippolytus and the Montanist Tertullian was that Callistus offered an edict that granted Communion to those who had committed adultery and fortification if they did penance. Callistus also took a controversial stance when he allowed lower clergy to marry and declared that noble women could marry those of lower classes including slaves. While his exact cause of death is unknown he is credited with having been a martyr and may have been killed during an uprising. His Feast day is celebrated on October 14.