There is a popular saying that suggests, “We are all atheists, I just believe in one less god than you do” used when replying to Christians (typically) on the charge of being “another atheist”.
The argument is based upon the idea that primitive man’s belief in many gods (pan-theism) has evolved into a belief in one (mono-theism) and that one less god equals no gods at all.
It’s true that the three great monotheistic religions are all descended from a common ancestor and even have sects analogous to species and sub-species - hey, there’s evolution again - but the very idea that atheists believe in fewer gods (1 - 1 = 0) is flawed.
The problem with the argument is one of semantics.
Theist (theology, theologian, etc.) all derive from the greek word “theos” meaning god. However, the critical thing to realise is that prefixing many words “a” actually negates or reverses their meaning. Some dictionaries define the a- prefix as “without”, others have it as “not” but the sense is the same.
Aplastic anemia is an interesting example because both words use the “a” to negate the meaning of the original root words (both of which are greek or ancient greek).
OK, so to atheist. We can see from this that our word atheist descends from a-theos and it’s here the response presented earlier becomes fallacious. Atheists are without god so to suggest in any manner that any monotheist is an atheist who’s lost the other gods is semantically incorrect. This because both the pantheist (pan- = many) believer in many gods and the monotheist (mono- = one believer in one god) are both theists.
I mention this is because I’ve seen the argument used on this site and the last thing I wish to see is one of us being hung by our own petard (which, by the way, means blown up with your own gunpowder).