Regarding the quotes from the historian 
Josephus about Jesus

     Flavius Josephus was a Jewish priest at the time of the Jewish Revolt of A.D. 66.  He was captured by the Romans, imprisoned, set free and then retired to Rome where he wrote a history of the Jewish Revolt called the "Jewish War."  Later he wrote "Antiquities" as a history of the Jews.  It is in Antiquities that he mentions Christ.  The mention is called the Testimonium Flavianum (Ant. 18.63-64; see below).  Josephus was born in Jerusalem around 37 A.D.  He died around the year 101. 
     The problem with the copies of Antiquities is that they appear to have been rewritten in favor of Jesus as they are very favorable, some say too favorable to have been written by a Jew.  Add to this that the Christians were the ones who kept and made the copies of the Josephus documents throughout history and you have a shadow of doubt cast upon the quotes. 
     However, all is not lost.  First of all, there is no proof that such insertions into the text were ever made.  They may be authentic.  The Testimonium is found in every copy of Jesusphus in existence.  Second, Josephus mentions many other biblically relevant occurrences that are not in dispute (see outline below).  This adds validity to the claim that Josephus knew about Jesus and wrote about Him since he also wrote about other New Testament things.  Nevertheless, though there may be some Christian insertions into the text, we can still reconstruct what may have been the original writing.
     Two researchers (Edwin Yamauchi and John P. Meier)¹ have constructed a copy of the Testimonium with the probable insertions in brackets and underlined.  The following paragraph is Yamauchi's:

“About this time there lived Jesus, a wise man [if indeed one ought to call him a man.] For he was one who wrought surprising feats 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 Christ.] When Pilate, upon hearing him accused by men of the highest standing amongst us, had condemned him to be crucified, those who had in the first place come to love him did not give up their affection for him.  [On the third day he appeared to them restored to life, for the prophets of God had prophesied these and countless other marvelous things about him.] And the tribe of the Christians, so called after him, has still to this day not disappeared.”

     Though this may be a correct assessment of the Testimonium, we should note that an Arabic version (10th Century) of the Testimonium (translated into English) is in basic agreement with the existing Josephus account:

"At this time there was a wise man who was called Jesus.  And his conduct was good, and he was known to be virtuous.  And many people from among the Jews and the other nations became his disciples. Pilate condemned him to be crucified and to die. And those who had become his disciples did not abandon his discipleship. They reported that he had appeared to them after his crucifixion and that he was alive; accordingly, he was perhaps the Messiah concerning whom the prophets have recounted wonders."² 

    The Arabic version was copied from a Greek version.  What is not known is which one?  But if you notice the comparison below, if the Arabic version was a direct translation of the Greek, then why the differences?  Nevertheless, what is important in the Arabic Version is that the resurrection of Christ is maintained.

     To summarize, the Testimonium Flavianum cannot be so easily dismissed as pure Christian interpolation (insertion into the text).  Though it seems probable that interpolation did occur, we cannot be sure what was added.  Also, the Arabic version contains very similar information as the Greek one regarding Jesus in His resurrection.
     Even if both versions have been tampered with, the core of them both mentions Jesus as a historical figure who was able to perform many surprising feats, was crucified, and that there were followers of Jesus who were still in existence at the time of its writing.

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1.     Edwin Yamauchi, “Jesus Outside the New Testament: What is the Evidence?” in Jesus Under Fire: Modern Scholarship Reinvents the Historical Jesus. Edited by Michael J. Wilkins and J. P. Moreland ( Zondervan, 1995): 212-4. And 2) John P. Meier, “Jesus in Josephus: A Modest Proposal,” Catholic Biblical Quarterly 52 (1990): 76-103.
2.     Arabic summary, presumably of Antiquities 18.63. From Agapios' Kitab al-'Unwan ("Book of the Title," 10th c.).  See also James H. Charlesworth, Jesus Within Judaism.