600 years ago: The death of Antipope John XXIII

On December 22, 1419, Roman Catholic Antipope John XXIII died at the age of 49. John XXIII, born Baldassarre Cossa, obtained doctorates in civil and canon law, and entered the service of Pope Boniface IX during the Western Schism, when there were rival claimants to the papacy in Rome and Avignon. Dr. Cossa was one of seven cardinals who deserted Pope Gregory XII in 1408, and became the leader of the Council of Pisa, which was convened with followers of Antipope Benedict XIII. In an attempt to end the schism, the Council deposed both Gregory XII and Benedict XIII and elected Alexander V as antipope, resulting in three rival claimants to the papacy. Alexander V died soon thereafter, and Dr. Cossa became Antipope John XXIII on May 25, 1410, having been ordained a priest just the day before. John XXIII was recognized as pope by France, England, Bohemia, Portugal, parts of the Holy Roman Empire, and northern Italian city states including Florence and Venice.

The Council of Constance was convened in 1413 as another attempt to end the schism; Antipope John escaped down the Rhine River to Freiburg im Breisgau, but was returned to Constance, where he was tried for heresy, simony, schism, and immorality. According to British historian Edward Gibbon, "The more scandalous charges were suppressed; the vicar of Christ was accused only of piracy, rape, sodomy, murder and incest."

Antipope John XXIII was imprisoned in Germany after being convicted. He was freed in 1418 after a heavy ransom was paid by the Medici Bank, and died in Florence, where he had been made Cardinal Bishop of Frascati by Pope Martin V. When Angelo Roncalli acceded to the papacy in 1958, there was some confusion concerning the numbering, but he took the name John XXIII.

Remember, according to Roman Catholic doctrine, we're supposed to regard the Bishop of Avignon Pisa Rome as the Vicar of Christ, i.e., a substitute Christ on Earth:

882 The Pope, Bishop of Rome and Peter's successor, "is the perpetual and visible source and foundation of the unity both of the bishops and of the whole company of the faithful."402 "For the Roman Pontiff, by reason of his office as Vicar of Christ, and as pastor of the entire Church has full, supreme, and universal power over the whole Church, a power which he can always exercise unhindered." Catechism of the Catholic Church