Commodus, looked favorably on the Christians at the onset of his reign. His son Caracalla had been raised by a Christian nurse, and the emperor himself had been cured of some ailment by a Christian. However, Severus later reversed his position toward the Christians, probably due to their unpopularity with the Roman pagans, and he issued a decree forbidding any person to become either a Jew or a Christian. The persecution commenced once again.
Zephyrinus was a Roman and the son of Habundius. Some sources indicate that his strength did not lie in leadership, but that he depended greatly on the more capable and practiced Calixtus, who, since his release from the labor mines, had been rehabilitated and devoted himself to the Church. Consequently, he was appointed archdeacon. Not only did he direct the lower clergy for Zephyrinus but he was also entrusted with the administration of the official cemetery which the Church now owned.
Heresy stormed the Church from all sides, but Zephyrinus adhered firmly to the doctrine set forth by the apostles. The excommunicated tanner Theodotus continued to teach that Christ was not the true Son of God. He had even gone so far as to set up his own church and place a paid bishop in residence. This bishop, called Natalius, had previously been tortured for confessing the true faith. According to legend, angels were sent to Natalius in visions to rebuke him for joining Theodotus, since Jesus did not want anyone who had suffered for Him to be cast out of the Church. Natalius appeared to have seen the light; he threw himself upon the mercy of Zephyrinus and begged to be pardoned. Natalius was readmitted to communion by the bishop of Rome after considerable penance.
Zephyrinus decreed that all ordinations, even those of mere clerics, be performed before the assembled clergy and laity.
Another heresy, called Modalism, taught by Praxeas, Noetus, and Sabellius, was brought to the attention of Zephyrinus. Followers of this theory obliterated the distinctions between the entities of the Trinity. Zephyrinus immediately condemned this, again citing the original teachings of the apostles.
Zephyrinus was said to have been martyred and was buried in his own cemetery on the Appian Way.