Person

Josephus

Flavius Josephus (c. AD 37 to c. 100), born Yosef ben Matityahu, was a first-century Jewish historian and military leader. He survived the Jewish revolt of AD 66 to 73, became a Roman client of the Flavian dynasty, and produced the most extensive surviving body of Jewish history from the Second Temple period. His two main works, The Jewish War (c. 75) and Antiquities of the Jews (c. 93 to 94), are the most important outside source for the historical Jesus. Together with Tacitus, he is one of the two load-bearing pillars of the extra-biblical case for the historical existence of Jesus.

Life

Born into a priestly family in Jerusalem around AD 37, Josephus received a standard upper-class Jewish education. He reports that, before settling on the Pharisees, he investigated all three major Jewish sects of his day: the Pharisees, the Sadducees, and the Essenes (a separatist Jewish community sometimes connected with the Dead Sea Scrolls). He served as a young commander in the Galilean military when the Jewish revolt broke out in AD 66. After Vespasian's forces took the fortress of Jotapata in AD 67, Josephus surrendered. In a now-famous incident, he predicted to Vespasian that Vespasian would become emperor. When the prediction came true in AD 69, Vespasian freed Josephus and made him a client. Josephus took the family name Flavius and spent the rest of the war as an interpreter and go-between for Titus during the siege of Jerusalem (AD 70).

After the war he settled in Rome, received Roman citizenship and an imperial pension, and spent the rest of his life writing. He died around AD 100, having outlived three Flavian emperors.

Works

The Jewish War (Bellum Judaicum, c. AD 75), seven books on the revolt of AD 66 to 73, written in Greek for a Roman audience. The eyewitness sections are unique evidence for the war and for the destruction of the Second Temple.
Antiquities of the Jews (Antiquitates Judaicae, c. AD 93 to 94), twenty books running from creation through the eve of the Jewish revolt. This is the most extensive surviving Jewish history of the Second Temple period and the main source for the Hasmonean dynasty, the Herodian rulers, and Jewish life under Rome.
Against Apion (c. AD 95 to 100), a defense of the antiquity of the Jewish people and of Jewish law against Greco-Roman slanders.
The Life (Vita, c. AD 95), an autobiographical defense of his own conduct during the revolt; attached to later editions of Antiquities.

References to Jesus

Josephus mentions Jesus of Nazareth in two places, both in Antiquities. Together they form one of the strongest pieces of outside evidence for Jesus' historical existence.

Antiquities 18.3.3, the Testimonium Flavianum

The famous passage at Ant. 18.3.3, in the Greek text that has come down to us, contains three phrases no non-Christian Jew would have written:

"He was the Christ" (ho Christos houtos ēn)
"if indeed one ought to call him a man" (eige andra auton legein chrē)
"he appeared to them alive on the third day"

The wholesale-forgery thesis (the claim that the entire passage is a later Christian insertion) fails on three independent fronts:

Manuscript-version evidence. Arabic (Agapius of Hierapolis, 10th c.) and Syriac (Michael the Syrian, 12th c.) versions of the passage preserve a less-Christianized text, which is plausibly closer to the original. Agapius reads "he was perhaps the Messiah" rather than "he was the Christ," which is exactly the kind of distancing language a Jewish historian serving Roman patrons might use.
Vocabulary analysis. Detailed studies (Meier, Vermes, Theissen) find typical Josephan turns of phrase in the neutral core of the passage, the kind of Greek Josephus uses but that Christian writers do not.
Origen's testimony. Origen (Contra Celsum 1.47) explicitly says Josephus did not believe Jesus was the Messiah. That is direct early evidence that the unedited passage Origen knew did not contain the line "he was the Christ." It points to a neutral original later overlaid with Christian additions.

The mainstream scholarly position, then, is: authentic core + Christian additions over the top. Not wholly fabricated, but also not wholly authentic as we now read it. The reconstructed core typically includes the points that Jesus was a teacher and wonder-worker, drew both Jews and Greeks, was crucified by Pilate at the urging of leading Jews, and that his followers persisted after his death.

Antiquities 20.9.1, the James passage

The second reference, at Ant. 20.9.1, describes the stoning of "the brother of Jesus, who was called Christ, whose name was James" (ton adelphon Iēsou tou legomenou Christou, Iakōbos onoma autōi) by the high priest Ananus in AD 62. This passage is almost universally accepted as authentic for several reasons:

The distancing phrase tou legomenou Christou ("who was called Christ") is what a non-Christian historian sorting between several men named Yeshua would write. It is not what a devout Christian forger would produce.
The wording uses Jesus to identify James, not the other way around. That is what a historian does when "Jesus" has already been introduced to the reader earlier, i.e., in the Testimonium. This internal cross-reference is itself evidence that some form of the Testimonium existed earlier in the text. Without the Testimonium, the James passage's identifying logic does not work.
Origen cites this passage, which pushes any interpolation hypothesis impossibly early. By the early third century, a forger would have needed to access manuscripts in multiple Christian centers and insert the same line in all of them, which is implausible.

This second reference is the strongest single piece of extra-biblical evidence for Jesus' historicity. Even scholars highly skeptical of the Testimonium accept Ant. 20.9.1 as genuine.

Other Christian-adjacent references

Josephus also mentions:

John the Baptist (Ant. 18.5.2), an extensive treatment of his preaching and his execution by Herod Antipas; broadly consistent with the Gospel portrait but written from a different angle (Herod's political worry about John's popular following).
The high priest Ananus (Ant. 20.9.1), the same Ananus who illegally executed James was deposed three months later. Josephus' tone is critical of Ananus, not of James.
Numerous other figures known from the Gospels and Acts: the Herods, the procurators, Caiaphas, Quirinius's census, and others. The political and chronological backdrop of the Gospel narratives is broadly corroborated by Josephus.

Apologetic significance

Josephus' value to the historical-Jesus case is structural, not rhetorical. He is:

A non-Christian Jewish writer working under Roman patronage, with no motive to invent Jesus.
Writing within about 60 years of the events.
Independent of the Christian source tradition. He is not citing Christian writings or repeating Christian claims.
Geographically and culturally close to the events. He was born in Jerusalem and lived through the Temple's destruction.

Together with Tacitus (a hostile Roman senator, Annals 15.44, c. AD 116), Josephus 20.9.1 forms the Tier 1 load-bearing layer of outside attestation. The reconstructed core of the Testimonium sits in the corroborating tier. See Extra-Biblical Case for Jesus, Objections and Responses for the full hierarchy.