The Roman stuff can be dated from all sorts of records but what do we have to date Paul? All we have is an account by a writer we know as Luke but we don't know when or where it was written and the letters which claim to be from Paul. We have no record anywhere outwith the NT for anything of this - not Paul birth date or the date he died - there is no record of the trials he is supposedly was tried at. There is literally nothing to go on. Now, its fine for anyone to come up with a date from something but thin of this
I'd have to delve into the scholarship a bit more, but as I understand it, the "authentic" epistles of Paul are dated prior to 66 C.E. because they make no mention of the Jewish War or the destruction of the Temple, which had an enormous impact on First Century Judaism. The pseudoepigraphical Pauline epistles are viewed as such because they differ theologically from the "authentic" Pauline epistles, or because they do things like assume the existence of a developed Church hierarchy with "bishops" and "deacons" and so on (the "Pastoral" epistles), which would not have existed in Paul's time.
Paul's theology is far more developed than the gospels - especially his Christology - yet people buy in to the idea that Paul taught first and then the gospels, which apparently didn't know anything of Paul's teachings become more primitive. It's not that likely.
I'm not so sure. This assumes that "primitive" theology is necessarily older than "developed" theology. How do we know that early Christianity did not suffer from a kind of "Idiocracy" in which the theology was dumbed-down to gain wider appeal? We can observe that such theological regression happens by comparing the writings of, say, Thomas Aquinas with sermons of the average televangelist.
Like Paul's epistles, the Book of Hebrews also contains a developed Christology, where Jesus is a celestial redeemer who offers his blood in a Heavenly Temple of which the Jerusalem Temple is merely a copy, in the sense of Platonic metaphysics. Its extensive contrast between Jesus as a celestial High Priest and the human High Priest in Jerusalem, with argumentation for why the former is superior, is presented as if the Temple is still in operation.
The Gospels, on the other hand, include "prophecies" placed in the mouth of Jesus, proclaiming that the Temple and the city of Jerusalem would be destroyed by the Romans. On the premise that it is more likely that the texts would be written after the events described, than that a man could foretell the future, the Gospels are dated after 70 C.E., with Mark as the first and the others appearing later.
If the "mythicist"
theory of Christian origins is true, then it would not be a surprise to see the sophisticated, mystical and philosophical theology come first, having its origins with educated, cosmopolitan Jewish mystic-philosophers aiming to reconcile Judaism with the prevailing currents of Mystery School teaching. This would have been followed by a trend toward "drawing down" Jesus into an earthly life for various reasons (e.g. to "explain" the events of the Jewish War as punishment on the Jews for crucifying Jesus, to establish a basis for a doctrine of "Apostolic Succession" as justification for the emerging proto-Catholic clerical hierarchy, to appeal to the common people, etc.).
It is arguable that the Gospels (at least Mark and Matthew) were not written as history, but as parables
about Jesus. Evidences for this can be found in the way that Gospel writers rearrange, insert, or omit "events" in their stories of Jesus, and otherwise demonstrate that literary concerns (storytelling) trump any supposed effort at "accuracy." Examples are plentiful, such as the writer of a later Gospel creating a different narrative context for a "saying of Jesus" than the one employed by a Gospel he was using as a source. The Gospel of Thomas provides evidence that "sayings of Jesus" were in circulation apart from any narrative context in a "life of Jesus." If so, these "sayings" might have been initially received and circulated as "channeled" revelations from a wholly celestial Jesus.
I'm not sure which model (historicist or "mythicist") is accurate, as there are a lot of heavy-duty scholarly writings on both sides, and the data we have is pretty sketchy. The "mythicist" model seems more parsimonious and makes more sense to me, but the majority of experts still lean toward historicism. As I understand it though, that same scholarly consensus also holds to the authentic letters of Paul pre-dating the Gospels.