So I've done a bit of fishing (not deliberate figure of speech, but hey, leave it in) and come up with the following sites. In some cases self described as esoteric or occult, with references to Atlantis, the Hyperboreans, and Primordial Tradition (capitalised). I could find no vestige of a beginning in most, or source for what is stated with such confidence. One is supposedly an ancient document. My search terms were "Oannes, bishop, Vishnu"

Oannes

Fisher Kings

comparative religion?

Seeking truth?

Look, the merovingians are in on it!

And Celtic Christianity

A primary source text

There's more out there. If you are interested.

Penny