See maybe the first ever time travel was tested on a doctor from the future. When he goes back to the choosen time (Some time while Jesus was alive) he realises there seems to be no magical man named Jesus.
he of course is stuck there and so tries making a life there with a story of how he was born and such. he uses his futuristic knowledge of disease and illness' and cures them.
people from those times would of been amazed at how much he could do with medicines.
and from a time where religion and faith could get you killed its highly likely they would try explaining his medical know how as Godly.
sorry if this offends anyone. I realise I havent typed it sensitively due to my lack of knowledge of different words.