Today is the feast of SS. Pontian and Hippolytus. They were enemies. St. Hippolytus of Rome was perhaps the most brilliant Roman theologian of the second century. He fell out with the popes; possibly he accused Pope St. Zephyrinus of the heresy of modalism, but very definitely he criticized Pope St. Callixtus for laxness; St. Callixtus would, contrary to custom, impose no penitential period on repentant schismatics and claimed that he had the authority to absolve the sins of adultery and murder for those who repented of them, without requiring any further penance, and he gave special dispensations for counting concubinage as marriage. An anti-Callixtan party rose up among many of the clergy of Rome, with St. Hippolytus at their head, and things got so bad between them that the anti-Callixtans broke away and elected St. Hippolytus their pope, making Hippolytus one of the earliest antipopes, and (unless you count maybe-Saint Felix II) the only antipope on the calendar of saints. St. Callixtus was martyred and succeeded by Pope St. Urban I; the schism continued. Pope St. Urban I died, apparently in relative peace, and was succeeded by Pope St. Pontian; the schism continued. There was a wave of persecution in Rome under Emperor Maximinus, and St. Pontian got wind that he was almost certainly going to be arrested, so in order to preserve the succession, he became the first pope to resign from the office, and was succeeded by Pope St. Anterus. Pontian was indeed arrested and sentenced to hard labor in the mines of Sardinia, where he died. Hippolytus was arrested in the same sweep, and also sentenced to hard labor in the mines of Sardinia, where he died. St. Anterus died and was succeeded by Pope St. Fabian. As the persecution was winding down and Fabian was apparently quite good at negotiating, Fabian negotiated the return of the bodies of both St. Pontian and St. Hippolytus from the Roman government. He buried them both with honors and entered them both as martyrs in the Roman Martyrology. It healed the schism, one of the few things Fabian was able to do, because a new Emperor led to a new sweep of persecutions, and St. Fabian was arrested and executed.
There are accounts according to which St. Hippolytus and St. Pontian were reconciled with each other, some say before the persecution, some say in the mines. But all of these accounts are quite late, and could very well be hypotheses about why St. Hippolytus of Rome, Martyr and antipope, is celebrated on the same day as his opponent, St. Pontian, Pope and Martyr. We don't really know at all. But, one way or another, the brotherhood of martyrdom is itself a great reconciler.
From a fragment of what seems to be St. Hippolytus work,
The Refutation of All Heresies:
The Logos alone of this God is from God himself; wherefore also the Logos is God, being the substance of God. Now the world was made from nothing; wherefore it is not God; as also because this world admits of dissolution whenever the Creator so wishes it. But God, who created it, did not, nor does not, make evil. He makes what is glorious and excellent; for He who makes it is good. Now man, that was brought into existence, was a creature endued with a capacity of self-determination, yet not possessing a sovereign intellect, nor holding sway over all things by reflection, and authority, and power, but a slave to his passions, and comprising all sorts of contrarieties in himself. But man, from the fact of his possessing a capacity of self-determination, brings forth what is evil, that is, accidentally; which evil is not consummated except you actually commit some piece of wickedness. For it is in regard of our desiring anything that is wicked, or our meditating upon it, that what is evil is so denominated. Evil had no existence from the beginning, but came into being subsequently. Since man has free will, a law has been defined for his guidance by the Deity, not without answering a good purpose. For if man did not possess the power to will and not to will, why should a law be established? For a law will not be laid down for an animal devoid of reason, but a bridle and a whip; whereas to man has been given a precept and penalty to perform, or for not carrying into execution what has been enjoined.