14 October - Calixtus or Callsite became a Christian as an adult. He worked - as a slave - in the service of a high official of the Emperor Commodus, named Carpophorus, who was also a Christian.

His master, who esteemed him, entrusted him with the administration of his property, but he was unable to return it when the bank went bankrupt, panicked, fled, was finally caught and locked up in a dungeon. He was condemned to the salt mines of Sardinia. He worked as a convict for three years to extract the ore, showing devotion to the other convicts.

Marcia, the Emperor's mistress of the time, Commodus, was a Christian and knew the young Calixtus, and got him freed and set free around 190. He spent a few years in Antium, south-east of Rome, on a mission for Victor I and took the time to cultivate himself. Zephyrin, as soon as he was elected pope in 199, called him to his side, making him his personal secretary as well as archdeacon of the city.

Calixtus was also the creator of the first Christian cemetery which was built in the tufa on the Via Appia and which today bears the name "Catacomb of St. Calixtus". During his five-year pontificate, he recognized as valid the marriage between slaves and free women and accepted the remarriage of widowers and their eventual entry into the clergy. In addition, he established the custom of absolving all sins. Finally, he was an experienced financier, a rare phenomenon at the head of the Roman Church, who gave the latter a prosperity unequalled until then.

He died on October 14, 222 in his district of Trastevere, victim of a riot directed against the Christians, during the assassination of Emperor Elagabal. He was defenestrated and then thrown into a well covered with rubble and removed by a priest a fortnight later. He was hastily buried at the foot of the Catacomb of Calepod's staircase on the Via Aurelia. To this day he is the first bishop of Rome whose grave has been found. It was in the fourth century that Calixtus was declared a martyr and then canonized.