Callistus was a former slave who became bishop of Rome in 217. Once he obtained his liberty, he was ordained deacon by Pope Zephyrinus and succeeded him in the Chair of St Peter. He fought against the Adoption and Modalist heretics. He preached God’s mercy for repentant sinners, despite meeting the criticism of ‘rigorists’ such as Tertullian. He was crowned with martyrdom in 222 and was buried on the Aurelian Way. He is best remembered for the Roman catacomb that bears his name, where many of the victims of anti-Christian persecution were buried. – CTS New Daily Roman Missal 2012, p 3060; Christian Prayer 1990, p 1253
