Legion, I'm aware of pretty much all the non-Biblical sources people turn to to try and present as evidence that Jesus (or Paul or any of the others) existed.
That's never really the problem. Generally speaking, those who haven't studied ancient history aren't really familiar with the nature, paucity, quality, and other short-comings of our evidence for most of ancient history. Historians (and no, not just biblical scholars) don't bother questioning whether Paul exists because the logic behind such radical skepticism would mean we can't trust much of anything anybody has ever written. As virtually all historians believe that authors from ancient history (as well as people in general, in other forms of evidence) preserved information we can scrutinize critically, they don't apply one standard of evidence when it comes to Christian sources and another when it comes to Greek or Roman.
In other words, historians recognize that the NT is a historical source, even those who (contra the majority) don't believe the gospels to be part of a genre of ancient biography of the type Plutarch, Suetonius, Philostratus, etc., wrote. After all, they use Aristophanes' fictional drama
The Clouds, the fictional character used by Plato which is in clear contradiction with the Socrates of Xenophon that Aristotle tells us was part of a genre of fiction started by one Simon the Shoemaker, etc.
Even those extremely critical of our ability to uncover historical elements within our earliest Christian sources have determined over and over again that their existence can't be explained without their being an historical Jesus behind them.
However, it is little understood how historians generally interpret what kind of evidence is available such that the historical figures we are all taught about in summaries in school are somehow "historical". The fact that historians use e.g., a major Greco-Roman biographer like Diogenes Laertius some of whose biographical subjects had died centuries ago and whose works barely survive passes uncritically. The heavy reliance on myth and legend is likewise glossed over because few actually bother to
read the primary sources for figures from antiquity. And then of course there is always the comparison between our sources for Jesus and figures so momentous as Julius or Augustus Caesar, rather than Euripides, Antiphon, Pilate, Pythagoras, Diogenes the Cynic, or even many of the names the authors of
The Jesus Mysteries proffer as "a list of Pagan writers who wrote at or within a century of the time Jesus is said to have lived".
None of them are contemporary and most
Contemporary is great. We rarely find contemporary sources for anybody from antiquity. For Jesus we have Paul, who is contemporary.
if not all, are questionable as to whether they are forgeries, interpolations or if they are even to reference Jesus in the first place.
In that case Christian sources are among the best we have. For most sources we have a few manuscripts that date from the late medieval period. Not counting quotations from early Christian literature or translations, we have literally thousands upon thousands of NT manuscripts so that NT textual critics have a comparative wealth of evidence to determine what is or isn't a forgery, interpolation, or variant.
I looked at the Amazon page for Robert E. Van Voorst's book and it doesn't seem to present anything new. Plus, that guy is a Christian theologian and a Presbyterian minister, so we know what conclusion he will draw.
Should we discount any atheists or agnostics who determine Jesus likely didn't exist? It is one thing to examine those like W. L. Craig's blundering attempts at historiography and dismiss them for the garbage they are. It is another to dismiss someone whose work you haven't read for a worldview that biases his the way that worldview's bias everyone. His is simply one of the most complete presentations of scholarship (including non-Christian and outside of biblical studies) on the state of research of our sources outside of the NT. If you wish for an historian you can examine Akenson, D. H. (2000).
Saint Saul: A Skeleton Key to the Historical Jesus. Oxford University Press. It's more credulous, but the author has a doctorate with the word "history" in it.
This is the problem with Biblical scholarship. They have a true conflict of interests and don't seem to be truly engaged in straight-up historical scholarship
What is your basis for comparison? What, for example, do you find problematic in Michael Grant's scathing dismissal of mythicism despite his prominence as a classical historian, not a biblical scholar? How about Richard Carrier's unquestioning use of Christian and non-Christian sources to reconstruct Roman "science" which includes legendary accounts barely surviving like that of Hypatia or is built upon the use of lists of names on a text which are unknown outside of that list to count the number of "scientists" and of what kind lived during the Roman period?
I didn't begin with historical Jesus studies but with classical languages and classical history. It was one of my majors. I'm used to looking at critical apparati that are vastly smaller than the manuscript evidence excluded from an NT critical apparatus because we have so many so vastly superior manuscript attestation. I'm used to studying figures whom we are not sure are equivalent of others by a similar name because almost nothing was written of them and what was supposedly written by them caused ancient authors to wonder if the two were the same. I'm uses to historians who rely on the Iliad as a source for historical information.
I was not used to the simultaneous credulity and completely unnecessary skepticism one can easily find in NT/historical Jesus studies, except in one case: Socrates. Even here, though, one historian can critically accept a select version of the account we have for Socrates, ignoring 300+ years of critical, skeptical assessment, while another in the very same volume can write all of our sources off as fiction. That was a few years ago.
The point is that historians of antiquity rely on historical methods (whether their doctorate contains the word "history", "classics/classical", etc.) and their work is reviewed by other historians across fields. It is well known that we have less evidence from this time. It is less well known how much the kind of sources we have for Jesus is greater than what we have for virtually any other figure from antiquity. People who refer to textual criticism (interpolation and other problems with our manuscripts) ignore or do not know that this problem is unbelievably worse when it comes to classical and late classical sources (even medieval!). The clearly mythical/legendary nature of the gospels is contrasted not with actually reading sources for those already accepted as historical (still less realizing we don't actually have them), but with some textbook or similarly summary version.
but are just trying to find "proof" for something they already believe in.
This is a natural human tendency. However, as the vast majority of historical Christian literature from it's beginnings in the 18th century, historical Jesus studies has undermined central Christian tenets. In particular, few conservative Christian scholars actually argue that history could possibly support Jesus' resurrection, while others disagree with e.g., whether Schweitzer's early 1900s account that Jesus was a failed messianic prophet mistakes an eschatological Jesus for the magician/egalitarian preacher whose body was eaten by dogs (as argued by the "big names" of the Jesus seminar and esp. by Crossan for that last bit).
That's why I'm skeptical of anything that comes out of those people.
"Those people."
Hm.