I am an atheist and I say “God does not exist”.
“Oh, you can’t say that… there might be a god somewhere!”
Yes, I can.
The “gods, or Gods” humans now worship have origins that are known. Even so, since the Jewish god can be dismissed, being impotent (Holocaust) and obviously having arisen during barbaric times (the wars, murders of innocents, and absurdities) then neither Christianity or Islam can be true. We now know how the Christian faith arose, and how it was fabricated from whole cloth. Christianity was needed to control slaves and the general citizenry. Islam is derived from both false beliefs, and so itself is false and easily dismissed (by the wise and non-ignorant).
What is left? An unknown god? Other faiths whose human origins are known? God as is commonly defined needs worship. There are no unknown gods soliciting worship. Therefore, there are no gods. Yet, there may exist an entity, however improbable, that might have started existence. An entity, a force, but most likely unconscious, unaware of our little speck of dirt orbiting around a very average star.
Does that make me an agnostic? No, I can say with fair certainty that gods do not exist. Gods need worship. There are no gods requiring worship, though some thing, some force or entity, however unlikely, might have started some ball rolling eons ago. The miniscule likelihood of that can be dismissed, or will be eliminated when the facts are all in, I am sure.
Remember, no manner of explanation will deter a “true-believer” who accepted faith without reason… how can reason apply there?