These comments are somewhat freely adapted from Willis Barnstone's essay on the historical bases of Jesus' life and death in the 2002 edition of his book The New Covenant (a translation of the Gospels and Revelation.)
Since the gospels are all we have as a detailed record of the life of Jesus/Yeshua, they are what we investigate and evaluate and about which we come up with guesses and broad theories. In short, all the historical events of Yeshua's life take place within the frame of unverifiable religious scripture.
One looks, of course, for the deepest meaning within a text, but always with the awareness that great religious scriptures of the world, in this and apparently all instances, are not tape recordings or photographs, but late transcriptions that have gone through an unknown plethora of transmission activity. The danger is to forget, especially during a lifetime of research, that so little is known.
It is hard for many scholars to move freely from nearly two millennia of theological exegesis to an unprejudiced walk through historical investigation. The holy precints of Christianity are a powerful tradition and fortress, and judgment contends with almost insuperable temptations to normative belief.
We have only guesses to describe the mysterious chemistry that turned a Jewish movement in Jerusalem into Greek Christan scripture. Where did the evangelists, who were not witness to these events, obtain their information? There is no knowledge about this void.
The sundry faces of Yeshua confound, but it must be remembered that an emerging new sect needs to erase its parent. We do not know even the most fundamental facts of the life of Yeshua - including the nature of his birth, the sect or segment of Jews (Essenes, Galileans, Zealots, Pharisees, Hasidim) whose views reflect his formation, the specific cause of his crucifixion. It should be clear that in the schizoid way in which Yeshua is presented - as [both] rabbi and denouncer of Jews - there is a deep confusion of conflicting disguises of identity, and diverse voices speaking through his persona.
This doesn't mean Barnstone is a mythicist (a position he seems to reject quite forcefully), but he is obviously a realist. His complete New Testament translation was released in 2009.