Were subatomic particles once thought to be supernatural?
Fair point, the analogy was flawed. Only intended to demonstrate that we can theorize what is not yet observed in nature.
Googling definitions for supernatural, didn't see anything about it meaning impossible or not existing. From Merriam-Webster: of or relating to an order of existence beyond the visible observable universe, from the Latin
supernaturalis, meaning beyond nature (am newbie, can't link yet). What definition are you using?
You said: "Supernatural isn't just 'unobserved', it is incompatible with Nature. A god that is observed in Nature becomes a part of Nature and therefore is not supernatural - and not a god!" (haven't figured out how to insert quotes yet). That's the point, a god hasn't yet been observed; at such time as one is, it would be part of our understanding of nature, assuming we could comprehend it in some meaningful way. But untill then, it is not categorically incompatible with or excluded from nature, but is characterized as beyond nature.
Re: alien example, I absolutely agree. Hard evidence trumps any supernatural explanations.
"God isn't just 'unobserved' in nature', he is
impossible" ( I really gotta take a minute to figure out quote insertion). Not by any definition or even logic that I can see. May I as by what means you can remove such a critter from the realm of
possibility? Not probability or reasonable conclusion from evidenced observation, but pure possibility.