"...just how Jesus was the son of such a being/concept."

it's perfectly easy to write a story which breaks known laws and introduces concepts that stretch credulity. Science Fiction does it every day; they just don't try to sell it as 'real', and most people don't TREAT it as real...(except maybe for the Darkover series by Marion Zimmer Bradley..*grin*)

a story that was written BY people who already had basic beliefs and no way to research, except by word of mouth and an occasional scribe, could EASILY create a myth that began to sound real. That is still being done today by various cults..witness the comet people and the Branch Davidians...(It makes only a little difference whether those who wrote the various manuscripts for the world's religions believed what they wrote...most probably did, and those who did a good job got 'believed')