Well, I think you misunderstand my hypothesis (or are strawmanning it). I’m talking about the fragmentation or transformation of shamanism, not the survival of full-blown shamanism in the subconscious. The religious themes of death and rebirth may echo the millennia of shamanic activity where the real religious experience lay in altered states of consciousness and a mad grasping at straws to solve social problems without any real divine oversight. What we call religious experience in the context of organized religion is often so much decadence and self-deception.
The preponderance of evidence is worth more or less depending on the nature of the inquiry. If we’re talking about ancient history where evidence is often scarce, we have to confront the fact that many of those inquiries may be inconclusive, because whatever direction the evidence points in, there may not be enough evidence to dispel rational doubts.
The main figures in ancient history such as Plato or Alexander the Great are posited to account for the documents that survive or for massive historical developments that show up in archaeological findings. In the case of Christianity, we need to posit authors of the documents of the New testament and members of the early churches. But that doesn’t require that we believe an historical man named Jesus was the founder of Christianity, since there were plenty of cults that sprang up by something like a comedy of errors, by syncretistic misunderstandings of myths and metaphors or an evolution of old ideas.
We know many of the elements of early Christian history. We know there were competing Jesus movements such as the Judaizers, the Pauline Son of God cult, the Q and Markan communities, and the Gnostics. Along with the Essenes, these were fringe Jewish or pagan cults that arose in the Hellenistic period in which there were all kinds of ideological mixing going on. Judaism was combined with the Greco-Roman culture not so much because of the work of a single founder, but because of social competition between the various Christian (quasi-Jewish) movements. One of those movements won out under the auspices of Constantine, and the rest were banned.
What matters to that history is the character Jesus as he’s depicted in the early Christian writings. There’s no need to posit an historical Jesus to make sense of that history, since those writings could have been mythical, metaphorical, or fictional. Most NT scholars believe Jesus was historical because their personal Christianity motivated them to study the NT in the first place.
As for the evidence you cite, it’s not so great, is it? We don’t know much about Paul’s dealings with the Church, because Acts is untrustworthy. Note that even some of Paul’s epistles are commonly disputed and are likely inauthentic. But it’s reasonable to believe Paul was starting Christian movements alongside the Jewish Christians and Gnostics, but again that shows only that there was organized religious activity at the time, not that the churches were started by an historical Jesus. On the contrary, Paul is clear that his churches were initiated by his “vision” of the risen Jesus which inspired his interpretation of the Jewish scriptures. It was common at the time for people to claim they saw ghosts or to interpret their personal inspirations and intuitions as the promptings of external spirits. Indeed, it’s still common today.
The famous passage in Suetonius is about Jews and Chrestus, not Christians or Jesus. For all we can tell, “Chrestus” could have been a misunderstood way of referring to “Christus,” to an apocalyptic messiah in general, which would mean the Jews that were kicked out of Rome were agitating based on general messianic fervor and weren’t necessarily directed by anyone.
The two passages in Josephus were likely interpolated by Christians and are thus inauthentic, as Earl Doherty shows, for example, in his detailed chapter in Jesus: Neither God nor Man.
I’m not saying, though, that the case for Jesus’s ahistoricity is overwhelming. In my view, the matter is indeterminate. I see his historicity and ahistoricity as two alternative scenarios we can entertain. Neither entails anything supernatural. I’m committed not to the nonexistence of Jesus but to the importance of considering the implications of his ahistoricity, given the scarcity and tenuousness of the evidence.