Athanasius (Pope)
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Pope Athanasius left Earth and founded a new Rome as a spacecraft some time prior to the 28th century. This was the result of a schism in the Catholic Church over the matter of the baptism of non-humanoid species. This led to riots, civil wars, and the fragmentation of secular authority that prompted Pope Athanasius to flee Earth.
Old Rome called this new Rome "Avignon" and they elected a rival Pope named Urban IX, who was considered an antipope by the new Rome. His successors also took this name up to Pope Urban XII in the 28th century. (PROSE: Companion Piece)