Christopher held the (anti) papacy from October 903 to January 904. Although he was listed as a legitimate Pope in most modern lists of Popes until the first half of the 20th century, the apparently uncanonical method by which he obtained the papacy led to his being removed from the quasi-official roster of popes, the Annuario pontificio. As such, he is now considered an antipope by the Catholic Church.
Little is known about the life of Christopher; the lack of reliable, consistent sources make it difficult to establish a concise biography. It is believed that he was a Roman, and that his father's name was Leo. He was cardinal-priest of the title of St. Damasus when he became Pope. His predecessor, Leo V, was deposed and imprisoned, most likely around October 903. As it is believed that Leo died in prison, Christopher may be regarded as Pope after his death. However, the account of Auxilius of Naples says that Sergius III murdered both Leo V and Christopher. An eleventh-century Greek document says that Christopher was the first pope to state that the Holy Ghost proceeded "from the Father and from the Son." However, the document claims that Christopher made this profession to Sergius, Patriarch of Constantinople. At that time, however, Nicholas Mystikos was Patriarch of Constantinople, making the account historically suspect. (Sergius I was Patriarch in 610–638, and Sergius II in 1001–1019.)
Christopher was driven from the (anti)papacy by Pope Sergius III (904–911). Hermannus Contractus contends that Christopher was compelled to end his days as a monk. However, the historian Eugenius Vulgarius says he was strangled in prison.