It took place, apparently, in the last years of Zephyrinus,[48] who died in 217. Hippolytus and his disciples fled from the—to them—polluted and heretical communion of the regular bishop and proclaimed that they and they alone were the true church of Rome. They were not numerous but their standing appears to have been high; at any rate they were able to find bishops willing to consecrate their leader to the episcopate. But their withdrawal left the “regular” church completely under Callistus’s control, and at Zephyrinus’s death he was elected to succeed him. This election, of course, Hippolytus treated as wholly null, asserting contemptuously that what Callistus had done was to become the leader of a “school of Callistans”, not of a “church of Christians”. Callistus disposed of the Christological controversy by excommunicating both Sabellius and Hippolytus, and then turned his attention to the most thorny practical question that perplexed contemporary Christians, the problem of mortal sin after baptism. From the beginning of the post-apostolic age[49] the church almost universally held that such sin could not receive absolution, so that the sinners were permanently excommunicate and without hope of restoration.[50] The only “orthodox” voice in opposition to this rigorism was raised by the Shepherd of Hermas, and even its author dared oppose the universal teaching of his age only because he had received a special revelation from God; nor did he venture to promise more than the remission of _one_ post-baptismal sin for anyone. In many quarters, indeed, even this mild relaxation of the rule was passionately resisted, and the most vigorous religious movement of the second century—Montanism—took as its watchword, “No second remission!”