To avoid what is known as 'circular argument', any sources on Historical Reliability of the New Testament must be extra-biblical and independent of the New Testament. Since it is impossible to prove that Mary was a virgin, but also the pagans and Jews of the middle of the first century did not go around saying things like "Mary was not a virgin", and since there is no contemporary evidence that Jesus did perform miracles or that he rose from the dead", we must to a large extent rely on historical criticism of the gospels and the other books of the New Testament.
Fortunately, critical scholars have identified the Gospel of Mark as the first New Testament to be written and there is, according to John Dominic Crossan (The Birth of Christianity, pages 110-111) a "massive consensus" that Matthew and Luke were substantially based on Mark. There is also a developing, although less complete, consensus that John was based on Luke. The consequence of these conclusions is that, to a large extent, we can focus on Mark's Gospel in our search for evidence of historicity in the life and mission of Jesus. Richard S. Hess says, in Israel’s Messiah, page 114, if even a significant fraction of this first written Gospel is historically accurate, the appropriate chronological starting point for this survey is Mark.
The resurrection of Jesus is the cornerstone of modern Christianity, yet Uta Ranke-Heinemann says, in Putting Away Childish Things, page 138, that theologians are by now in practically unanimous agreement that Mark 16:9-20 is a later interpolation. The original gospel provided no record of the resurrection, other than the word of a young man the women met in the tomb, and even they ran away, telling no one of what they saw and heard:
Mark 16:8: And they went out quickly, and fled from the sepulchre; for they trembled and were amazed: neither said they any thing to any man; for they were afraid.
If scholars are right in saying that Mark provided the narrative source for the other New Testament gospels, then there is not much evidence for the physical resurrection of Jesus. As for the historicity of the other gospel accounts, Ian Wilson says, in Jesus: The Evidence, page 143, because the Matthew gospel alone tells the story of the guard, the violent earthquake and the ‘angel of the Lord’ rolling away the entrance stone, it is probably safest to regard these as pious embroideries by an author demonstrably over-fond of the miraculous. Archbishop Peter Carnley, former Anglican primate of Australia writes in The Structure of Resurrection Belief:
The presence of discrepancies might be a sign of historicity if we had four clearly independent but slightly different versions of the story, if only for the reason that four witnesses are better than one. But, of course, it is now impossible to argue that what we have in the four gospel accounts of the empty tomb are four contemporaneous but independent accounts of the one event... There is no suggestion that the tomb was discovered by different witnesses on four different occasions, so it is in fact impossible to argue that the discrepancies were introduced by different witnesses of the one event.
My concluding remarks on the gospel come from David Rhoads, Joanna Dewey and Donald Michie, who say in Mark as Story, page 5, if we look through Mark as a window into history, we will think first of the historical figure Jesus rather than of Mark's portrayal of Jesus. They say we should read Mark as story rather than as history.
If there is no evidence that Jesus was physically risen from the dead, this is problematic for Acts of the Apostles, which gives a dramatic account of Jesus during the forty days following his crucifixion, during which he provided many proofs and was seen by many, until finally taken bodily up into heaven. Acts tells us of Stephen, the first Christian martyr, but Raymond E. Brown says, in An Introduction to the New Testament, page 320, we can never verify the existence and martyrdom of Stephen. Acts tells of Paul's conversion on the road to Damascus, an event that Paul himself never mentions, but Ranke-Heinemann points out (ibid, page 163) the conversion account has improbable parallels to the ancient play, the Bacchae by Euripides (d. 406 BCE): "It hurts you to kick against the goad[or 'pricks']" (Acts 25:14). That this short passage is not a coincidence can be established because the situation and context are the same, and Acts even has Jesus even uses the same plural form of the noun (kentra) that Euripides needs for the metre of his line. The story of Paul's escape from prison has reasonably close parallels to words in the play - Acts 16:26: "... and immediately all the doors were opened and everyone's fetters were unfastened;” Bacchae: "The chains on their legs snapped apart by themselves. Untouched by any human hand, the doors swung wide, opening of their own accord."
Michael Baigent reports in The Jesus Papers, page 11, that William Inge, Dean of St Paul’s Cathedral, was once asked to write on the life of Jesus. He declined, saying that there was not nearly enough solid evidence to write anything at all about him. Whatever the background of this anecdote, it does reflect the conclusion one could reach from the above analysis. There has been significant scholarly work to discern the reliability of the New Testament canon, but much of it points away from historicity of the New Testament. That does not mean that Jesus himself was not historical, just that those who wrote about him knew nothing of Jesus or what he actually did during his time on earth.