That's a semantic argument for God, one I haven't heard before, probably because it fails instantly. The definition of words (which you got wrong) are not arguments in favor of the objects of those words existing. Theists are "with" God in the sense that they hold the opinion (even the faith) that he exists. Atheists are without it in that they don't hold the opinion it exists. Theism isn't a restatement of a fact that God exists, that's a theological position. But that's a typical approach you take, using definitions instead of arguments. YES! If your idea isn't falsifiable, you've admitted that it's illogical. I think you do admit that your position is unsupportable by logic, reason, or science, so you lose the debate, by any reasonable measure. At least be honest and assert that you hold your beliefs with conviction for reasons compelling only to you and perhaps other theists.