During the Jewish War of 66-70CE, a Pharisee militia leader named Joseph bar Matthew, based on his own wonky studies of the End Times, came to the conclusion the commanding general on the Roman side, Titus Flavius Vespasianus (whom historians call “Vespasian”) was Messiah. Or at least that’s what Joseph told Vespasian after he was captured.
Vespasian was amused, and kept Joseph around as a slave and translator. That is, till he realized he had a really good chance to be emperor, seized it, and left Joseph in Judea with the new commanding general, his son Titus Flavius Vespasianus Junior (“Titus”). Titus is the guy who had Jerusalem burnt down and the temple destroyed in 70, and nine years later became emperor himself. He freed Joseph, and after gaining Roman citizenship, Joseph renamed himself Flavius Josephus after Titus’s family.
We best know Josephus as an historian, mainly for two of his Greek-language books: The Jewish War, a history from Herod the Worst to the end of the war, and his memories of it; and Jewish Antiquities, a history of Israel and Judea. It’s in The Jewish War, book 18, where he makes mention of John the baptist in a chapter about Herod Antipas’s war with Aretas, king of Arabia. (My translation.)
116Some of the Judeans are thinking Herod’s army’s destruction was from God, and rightly so—as punishment for his revenge on John, called “the baptist.” 117Indeed Herod murdered this good man. John was commanding the Judeans to be virtuous towards one another and pious towards God. He was using baptism to help them understand, for this ritual washing was acceptable to God—it will appear to him, not like a certain sin-offering, nor a prayer one could use, but like purifying the body. Therefore before one could be righteous, a soul was cleaned out. 118Those who gathered together to hear John were pleased at much of the teachings they heard. Herod feared John’s strongly persuaded people, lest some of them trigger a revolt, for everyone accepted and followed John’s counsel. Herod considered it better to do this before some new follower of John came to imagine a change in the system, and try something. 119On Herod’s suspicion, John was preemptively made a prisoner, and sent to the fortress Maherús to kill him. In the Judeans’ opinion, the destruction of the army became God’s punishment; he wanted to do evil to Herod.
We have no idea whether Josephus ever read the gospels, all of which had been written by the time of the war. Clearly he didn’t believe Jesus is Messiah… although some overzealous Christian got hold of Antiquities book 18, and altered the one passage which had anything to say about Jesus. Probably he found it blasphemous. Well now it’s not; it now says this, and is obviously not Josephus.
63At this time comes Jesus, a wise man—assuming it’s right to say “man,” for he’s a doer of paradoxical works; a teacher of people who are pleased to get the truth, who drew many Judeans and many Greeks. This man is Christ. 64On the evidence of the head men among us, Pilate ordered him to the cross. Not that those who first loved him stopped following, for he appeared to them alive again on the third day. The divine prophets had foresaid this, and other countless wonderful things about him. To this day the “Christians,” named for him, have not fallen as a tribe.
So it’s not outside the realm of possibility the bit about John the baptist was also altered, or inserted by Christians who wanted to make sure one of our prophets is in Josephus’s history.