Callistus was originally a slave in the imperial Roman household. Put in charge of the bank by his master, he lost the money deposited, fled, and was caught. After serving time for a while, he was released to make some attempt to recover the money. Apparently he carried his zeal too far, being arrested for brawling in a Jewish synagogue. This time he was condemned to work in the mines of Sardinia. Through the influence of the emperor’s mistress he was released and went to live at Anzio.
After winning his freedom, Callistus was made superintendent of the public Christian burial ground in Rome—still called the cemetery of Saint Callistus—probably the first land owned by the Church. The pope ordained him a deacon and made him his friend and adviser.
Callistus was elected pope by a majority vote of the clergy and laity of Rome, and thereafter was bitterly attacked by the losing candidate, Saint Hippolytus, who let himself be set up as the first antipope in the history of the Church. The schism lasted about 18 years.
After the death of Zephyrinus (217), Callistus was elected pope but was opposed by his theological adversary Hippolytus, who attempted to supplant him and who accused him of favouring modalist, or Patripassian, doctrines, both before and after his election. (Callistus, however, condemned and excommunicated Sabellius [fl. c. 215–c. 220], the most prominent champion of modalistic monarchianism, called Sabellianism, a heretical doctrine that denied personal distinctions within the Godhead.) Hippolytus also accused him of certain relaxations of discipline: it appears that Callistus reduced the penitential severities against fornication and adultery, which the church had previously regarded as irremissible except by God.
Callistus could not persuade Hippolytus’ followers of his rightful authority as Pope during his own lifetime. The Catholic Church, however, has always acknowledged the orthodoxy and holiness of Pope St. Callistus I, particularly since the time of his martyrdom.
Callistus was martyred during a local disturbance or anti-Christian mob in Trastevere, Rome in 222. According to the apocryphal Acts of Saint Callistus, Asterius, a priest of Rome, recovered the body of Callixtus after it had been tossed into a well and buried Callixtus’ body at night. He is the first pope—except for Peter—to be commemorated as a martyr in the earliest martyrology of the Church.