schism · 217 · Rome
Hippolytus was the most learned man in the Roman church and wrote in Greek when Rome had begun to speak Latin. He had already quarrelled with Zephyrinus; when Callixtus succeeded in 217 he refused him outright, on two counts. The first was penance: Callixtus was willing to readmit Christians who had committed grave sin after baptism, and Hippolytus thought the church had no such power. The second was doctrine — he accused Callixtus of blurring the Father and the Word into one, which is the charge his Refutation of All Heresies presses at length. A party set him up as bishop against Callixtus, and he held that position through Callixtus, Urban and Pontian: the first antipope, by a long way the most distinguished, and the only one this dataset carries. It ended in 235, when Maximinus deported both Hippolytus and Pontian to the mines of Sardinia, where the tradition says they were reconciled and where both died. That reconciliation is a clause in the persecution's own profile, and until now it referred to a schism this dataset had never recorded. The Roman church came to keep them together on one day, which is its own kind of answer.
To keep the Roman church from a bishop he judged unfit — too easy on penitents, and careless about the distinction between the Father and the Word.
Eighteen years of parallel churches in one city, ended by a persecution that deported both claimants to the same mine.