The word is not atheos, its atheist. Theist may have derived from the root theos, but the word theist very clearly means believer in a god or gods.
The spelling is different but the meaning is the same. So what I contend remains: If a theist believes in the existence of God, then an atheist believes in the non-existence of God.
You can continue being Mr. Science. I, however, am Mr. Language.
