Are there any extra-biblical accounts of the fact that Jesus Christ really was an historic figure ?
In Rome, in the year 93, Josephus published his lengthy history of the Jews. While discussing the period in which the Jews of Judaea were governed by the Roman procurator Pontius Pilate, Josephus included the following account:
The "Testimonium Flavianum":
"About this time there lived Jesus, a wise man, if indeed one ought to call him a man. For he was one who performed surprising deeds and was a teacher of such people as accept the truth gladly. He won over many Jews and many of the Greeks. He was the Messiah. And when, upon the accusation of the principal men among us, Pilate had condemned him to a cross, those who had first come to love him did not cease. He appeared to them spending a third day restored to life, for the prophets of God had foretold these things and a thousand other marvels about him. And the tribe of the Christians, so called after him, has still to this day not disappeared."
- Jewish Antiquities, 18.3.3 §63
(Based on the translation of Louis H. Feldman, The Loeb Classical Library.)