Supernatural Beings And Other Worlds

One premise for sf is that there are powerful beings that have been regarded as supernatural whereas fantasy assumes the supernatural. Fantasy premises include:

that supernatural beings were active on Earth in the past but have withdrawn;
that they are still present but concealed;
that mythological beings do exist but on other Earths in parallel universes;
either that each mythology has its own Earth or that there is an Earth where they all coexist.

In Poul Anderson's The Broken Sword, supernatural beings from every mythology coexisted on Earth in the historical past whereas, in his Operation Luna, there is a "goetic" universe where all such beings can be contacted although sometimes by traveling to yet another universe.

On the goetic Earth, the National Astral Spellcraft Association test flies spacecraft in New Mexico but encounters problems, e.g., moths eat a flying carpet. Consulting local medicine men, NASA learns that Coyote resents their invasion of his territory and their spectacular stunts. However, when the President of the United States ensures that the Indians get a better deal, the priests invoke the gods and kachinas to protect NASA. This is only to be expected. We all know that it is a tough job to be President of the United States!