Deism for non-believers

[FallentoReason]

I was thinking about the definition of atheist the other day. So we all should know by now that an atheist simply lacks the belief in a god and doesn't claim that said god doesn't exist. What is the only way of almost definitely saying a god can't exist though? If we define it entirely so that there are properties that can actually be 'tested' against what we know.

Imagine a hypothetical 'god scale' where at one extreme we have the most tangible definition of a god. This god undeniably exists because it's infact a creature that lives among us and will forever reign the earth meaning that all generations have witnessed it to date. At the other end of the scale we have a god that basically can't be detected and is merely responsible for creating everything. We can confidently say that the most tangible god doesn't exist. But the question is now, how far along the scale can we move saying that they don't exist until we get to a definition of a god that is plausible? It seems to me that Deism has to be the belief of a non-religious person because the amount of definable gods on the scale are endless. One is bound to stop somewhere along it and not be able to justify why that god couldn't exist.