As a young person growing up in a Christian home, I remember wondering if there was evidence outside of the gospels if Jesus of Nazareth ever existed. Between Two Worlds has an interview with Craig Bloomberg. In that article is this paragraph.
One can easily find blogs and websites claiming that Jesus never existed. Even if we didn’t have the New Testament, what would we know about Jesus from non-Christian sources?
The best source here for a book-length answer is Robert van Voorst’s Jesus outside the New Testament (Eerdmans, 2000). Here is my composite summary:
Jesus was a first-third of the first-century Jew, who lived in Israel, was born out of wedlock, whose ministry intersected with that of John the Baptist, who became a popular teacher and wonder-worker, who gathered particularly close disciples to himself, five of whom are named (though some of the names are a bit garbled), who consistently taught perspectives on the Law that ran afoul of the religious authorities’ interpretations, who was believed to be the Messiah, who was eventually crucified under Pontius Pilate, Roman procurator in Judea (which enables us to narrow the date for that event to somewhere between A.D. 26 and 36), and who was allegedly seen by many of his followers as bodily resurrected from the dead. Instead of dying out, the movement of his followers continued to grow with each passing decade and within a short period of time people were singing hymns to him as if he were a god.