Philip Pullman takes a conspiracy theory line when adding to his story of Jesus a theological overlay. This is helpful since, as so obviously wrong, it does point to what might have happened.
We have to imagine having been witnesses to the events of Jesus' ministry. Just think how radical it was; enough in itself to start a huge welling up of hope from those previously excluded from society. I suggest, though, that something else surrounded his death. We read of it as the resurrection; quite what it was we have no real way of knowing.
What then happened was men and women trying to make sense of it all. Inevitably they took the framework already avaialable fom Judaism and the Hellenic world. Yet I do not see this as conspiracy, merely an honest attempt to understand something truly extraordinary.