I see. So, in your mind, no one can disprove anything. If I say I can disprove the existence of unicorns, I actually can't, according to you. All I can do is show errors in how one defines unicorns. Sorry, that just doesn't cut it for me.
If you define something, and I can show that what you defined doesn't or can't exist, then I've disproven its existence.
Ah, you're falling into that trap. No, a lot of god-concepts are perfectly falsifiable. If they are not, they're not really worth considering. There are two concepts here. One is talking about a very general, vague godlike being. The other is talking about God as defined by people. I'll grant you that "God" in its most intentionally vague can't be disproved, but "God" when someone takes the time to define it, can be disproved. If the make it intentionally unfalsifiable, then it's a useless concept. (That's the entire point of the FSM and teacup examples.)