Humans can induce vision through the use of psychotropic drugs or other means.Whether thees are a connetion to the divine a matter of theological debate.I have yet to see a timeline inspired by a change in a divine revelation. But I suppose you raise a valid point. Seems to me I can manipulate any past character with divine intervention claims though. That's a flood gate.
A TL premise is I found interesting is to have a Hindu pundit travel to the Roman Empire and ending up in Germany. He believes there is a connection between the Teutonic Aesir and Vanir and the Hindu Deva and Asura. Working with the Teutonic priesthood they develop a syncretic religion based on the Teutonic pantheon with Hindu elements. Being literate he works with Teutonic priests to create religious texts detailing beliefs and practices. The existence of an organized priesthood and consistent religious dogma allows for successful resistance to Christian proselytizing.