More likely, the answer to why the old Gods went away can be found in this very interesting book: The Darkening Age The Darkening Age: The Christian Destruction of the Classical World: Nixey, Catherine: 9781328589286: Amazon.com: Books
As soon as Christianity became the state religion Christian’s set about destroying pagan idols, harassing pagan worshippers and christening pagan temples like some sort of ancient woke leftist mob. On a side note I find it humorous that the social justice movement was born in the Christian church which is now their arch enemy.
I believe all of the authors you site were writing at a time when Christianity was dominate or beginning to dominate through the power of the state.
But I do think you are on to something. I’ve often mused that Jesus is alive but as an egregore.
As for Richard’s quote I think he was wrong. To an ancient Torah reading Jew they would have recognized these words to be from the psalms reportedly written by King David who is ultimately saved and redeemed as is Jesus. The Gospels are actually very clever mythology.