Zephyrinus was born a Roman in the middle of the second century. He reigned as Roman bishop from 198-199 to 217.
Hippolytus, a rival, is our only extant source of biographical information on this pope. And much of it is probably exaggerated lies. Thus, he is described as a simple man without education who depended too much on his archdeacon. To be more accurate, we can look at the actions he took.
In the first three years of his bishopric, Zephyrinus had to put up with an increasingly negative view of Christians by the Emperor Septimus Severus. In 202 or 203, the emperor proclaimed an edict of persecution against Christians. Converting to this religion had terrible consequences. This edict remained in effect until Severus' death in 211. It is considered one of the worst of all the persecutions. The origins of this change of heart by the emperor may have been the Christians' refusal to honor the pagan culture, or it may have been that Severus was tired of the infighting among the various Christian sects which were now common. Zephyrinus, like the others of the faith, were obligated to stay quiet.
Callistus, the confessor who remained in Sardinia and who was given a stipend by the Roman Christians to preach there, was recalled to Rome about the time that Zephyrinus was elected. The Christians had purchased a cemetary on the Via Appia and needed someone to take care of it. Callistus was given that position. He also became the archdeacon and right hand man of the new pope.
Meanwhile, Theodotus, the Tanner, who had been excommunicated by Pope Victor, continued the preaching of his heresies and passed on his teachings to others. They taught that Jesus only became divine at his baptism. There was a man named Natalis, who had suffered greatly when persecuted. He lived through the persecution without denouncing the Faith. Somehow, the Theodotites convinced him to become a bishop within their sect, which he did for a while. Then he began to have nightmares, including one in which he was scourged all night by an angel. This made him think about what he was doing. Dressing in sackcloth, he went to Zephyrinus, begging forgiveness. He was granted forgiveness after a penance.
Another group, lead by Hippolytus, questioned the Trinity. He claimed that the Divine Logos was a separate person from God the Father, was not God at all, but a mediator between God and creation. Zephyrinus, not a theologian in his own right, did not see the fine distinctions sufficiently to argue them. And there were still the Montanists, or New Propheies sect and several other minor, less troublesome ones.
Hippolytus accused Zephyrinus of being too easy on great sinners, ie, Natalis, and not doing all he could to condemn all the heresies around him. Hippolytus grew more irritated with the Roman bishop and blamed Callistus for leading him astray. He also accused Zephyrinus of agreeing with the heretics and for undermining Chirstian discipline by not arguing with them.
There was much arguing against all these teachings but mostly by theologians in Asia Minor. It took much time to put these heresies to rest.
Emperor Septimus Servus died in 211. The next emperor, Caracalla, issued an edict in 212 proclaiming that Roman citizenship was opened to all free people of the Empire regardless of religion. Things between the Church and the State began to get better.
The "Liber Pontificalis" credits Zephyrinus with two decrees, however, there is no historical substantiation: Allowing First Communion only to those 14 and over, and allowing those excommunicated to get back into the good graces of the Church after penance.
Zephyrinus is buried in a separate sepulchre in the cematery named after Callistus in the Via Appia.
Pope Saint Zephyrinus, pray for us.