The difference is in the body. Suppose that things happened pretty much exactly as the gospels tell them. A bodily experience occurs after the death that is perceptually identical with the bodily experiences of companionship before the death. This is a sudden increase in introspective competence. The unconscious becomes more accessible.
Inner awareness becomes suddenly safer.
People open up to parts of themselves that were previously inaccessible. The only problem with this approach would seem to be that it might seriously violate the carefully constructed sense of presence in our bodies that we learn in contemporary culture. I suggest that in this culture we live very gingerly in our bodies. We live much more comfortably in our minds. If there is indeed this major difference between the experience of the original event and how we tend to experience it now, that would explain a lot of historical data, including the power of the event that started this civilization, and the weakness of the institutions that claim to carry it on now.