While you don't accept her as authoritative, I merely review the literature and provide it. It certainly seems like a lot of references. And there are numerous more.
It think this is the most important thing which needs to be addressed, so I hope you don't mind if I put it at the top.
A website isn't "literature." Roger Beck's various journal articles, books, and volumes are literature. So are the works of Burkert, Meyer, Ulansey, Rudolph, and any number of people who
1) Are or were specialists in relevant fields
2) Publish
research (technical literature) intended to advance their fields like actual scholars do
3) Don't lie or blatantly misrepresent their own sources.
She cites Roger Beck. Here's an article by him:
Mithraism
She does point out that the Mithras myth's have 3 distinct centers of worship. She also points out that not all of the similarities between Mithras and Jesus are shared by all three lines of the Mithras cult. Again she mentions that the Persian sect has been suggested to represent some other deity. What is significant, is that all these beliefs existed well before Christ.
How do we know? Perhaps some context not just to ancient history, but the history of this "Jesus/Mithras connection" as well. Why, for example, did Renan, Frazer, and others compare Jesus and Mithras as well as the Christians and initiates of the Mithraic mysteries? Simplistically, they simply assumed in general that because "paganism" was around before Christianity, all the borrowing went one way. This is important, because we don't have a single piece of evidence describing any practice, interpretation, or understanding of Mithras which is remotely comparable to the gospels or early christianity at all, until after the first century. There is not a single piece of evidence anywhere of any non-Roman version of a Mithra or Mithras which bears any resemblence to Jesus or how early Christians understood Jesus (and how they practiced their religion).
There is, however, some similarity between the Roman Mithras and Jesus, in that the Roman mysteries of Mithras seem to inolve (or perhaps revolve around) the idea of salvation through initiation. But
1) The earliest evidence of any worship of Mithras at all in Rome is at best dated to the end of the first century, and therefore after both Jesus and Paul were dead, Mark and perhaps all the gospels were written, and Christians were no longer a Jewish sect.
2) That earliest evidence tells us almost nothing. It is only the accumulation of the evidence as it unfolds in various ways over the second and third, and fourth centuries (although just what counts as evidence in late antiquity is a matter of contention).
3) Most of our evidence is symbolic, not descriptive, and therefore hard to reliably interpret.
What is
most essential to understand, however, is that over the past century it became blatantly obvious the assumption about one-way borrowing was wrong, flawed, incorrect, inaccurate, etc. The so-called Church fathers certainly borrowed from Greco-Roman philosophy, but Christianity influenced other religious practices across the empire. Some mysteries which predated Christianity changed through the influence of Christianity, and others seem to have been shaped from their inception in part by Christianity. Thus this:
Just becasue the persion version did not venerate the sun has little import. All of these views began to merge, as you reference, during the hellenistic period.
Has known to be wrong for the past hundred years.
Yet, thanks to the ever-present individuals, from Arthur Drews all the way to Murdock, this the same rehashed 19th century views somehow find a proponent who refuses to be disuaded by, well, scholarship.
The problem is that while those who wrote a century ago may be excused, people like Murdock, Freke & Gandy, etc., don't just rehash tired arguments, or fail to do adequate research. They lie. They misrepresent their sources. They manage to get their hands on books which have been out of print for decades or longer, but don't ignore a massive amount of actual scholarship apart from the few which they can quote out of context and misrepresent. I personally find that despicable, but then I have a certain bias against the spread of misinformation.
Murdock is not a historian, has not published a single work in any academic journal, published any paper in any academic volume, or published anything at all by any respected academic publishing company. She isn't cited by experts except the few that take the time to write non-technical works for the public to correct the misconceptions spread by people like her.