atheism defined

let me try to accomplish some clarification of the term 'atheism.' several people have written to say that my declaraton that 'i'd be surprised to meet god, but i don't say it's impossible' means that i'm an agnostic, or indeed a theist (?). of course, some thinkers have defined god as a necessarily existing being, and then inferred from this definition that god exists (the "ontological argument'). in that case it's sufficient to be an atheist to declare that it's possible that god does not exist.  only: as kant and many others have shown, the idea of necessary existence cannot be made comprehensible. now there could be a form of atheism that declares that god necessarily does not exist. the simplest such view would be an argument to the effect that the qualities attributed to god are absurd, that the attribution entails a contradiction. the most famous argument along these lines focuses on omnipotence and asks things like: can god create a rock so heavy even he can't lift it? if so he's not omnipotent. if not he's not omnipotent. therefore he's not omnipotent. but i feel that some conceptual legerdemain has taken place here as with the ontological argument. at any rate, the way i'd state my atheism is: i believe that god does not exist. here 'exist'  means just everyday existence, like the existence of you or me, or this basketball: if we inventoried the things in this world, we'd not find god. 'god' i'm going to take not as the proper name of something, but as an abbreviation for a set of descriptions: omnipotence, omniscience, omnibenevolence etc. so this atheism is the assertion that nothing that satisfies those descriptions exists. there's no modal claim at all. i'm not asserting that it's impossible that god exists, or denying merely that god necessarily exists; i am denying that god exists.
a classic brief attack on the arguments for god's existence: bertrand russell's "why i am not a christian."