negative God a sort of Un-god, In-god, De-god.
As I said, that's like asking for less than a vacuum, or colder than absolute zero.
Even in fantasy and magic, some things are just meaningless to ask for.
A "god" that does evil instead of good is frequent in Polytheism. There could conceivably be a monotheistic religion with only an evil supreme being. But that's purely perverse rather than "below" Atheism in the scale.
As I said, Atheism (no belief in existence of god(s), or usually supernatural at all) is two main camps, Atheists come in many flavours. Some illogically believe in life after death, the Rational Humanists do not. The main one supports the idea of "good", morality, justice, mercy, love etc as being things to be sought that don't need a god to validate them*. The other camp (quite logically actually) claims that there is no absolute good, absolute morality. That even justice, mercy, love, hate, good, evil etc are all artificial religious constructs, that if there is any morality, then it's what ever society decides today. Ultimately, the philosophy will believe only the strongest should survive and breed and makes Individualism more important than any responsibility to Society. Any means can justify the ends, and who can even dictate what the "ends" could be?
(* The problem then is how is it decided what is "good"? Where do these standards of Humanism come from? If you ground down the entire Universe and sieve it you can't find mercy, love, justice, kindness, honesty. Thus Nietzsche quite logically says these are all bogus. But Nietzsche would have
rejected Nazism as totally bogus too, as simply being the other side of the coin so to speak of Judeo-Christian values. See also
this article).
So there is no level of "god belief system" below Atheism. But at Atheism level, I think, you can have three camps:
- "Liberal" Humanists. They do not endorse Nietzsche
- Individualism and Anarchy based on Nietzsche's actual philosophy. Note that Anarchy and pure communism are political systems that probably only work for Angels. People are too greedy and selfish.
- Totalitarian Atheism (of extreme Fascism or Stalinist "Communism"**!). It's interesting that Lenin, Stalin and Hitler/Nazis all suppressed Esperanto and leaders killed! The leading Esperanto group in the 1920s was a Socialist International group! The Facists particularly (still) use distorted versions of Nietzsche's philosophy to justify their philosophy.
(** Stalin wasn't a real communist. Probably the Bolshevik Soviets killed, exiled or suppressed "real communists")