Does the following successfully establish a presumption of strong global atheism?
"Define strong global atheism as the view that there is no god. There is a presumption of strong global atheism because theists propose the addition of a supernatural entity (a god) to what is already known to exist (the natural world).
That is, theists make an extraordinary claim, and extraordinary claims require extraordinary evidence. In the absence of such evidence, strong global atheism is warranted."
I'd say no. (By the way, I'm not sure what "strong global" adds to "atheism," but let that pass.) The trouble is that the argument begs the question against various forms of theism. To state the most obvious problem, there are plenty of theists who think that God is already known to exist and has been for millennia. Now perhaps these theists are wrong, but in this context one can't simply assume that without argument. Nor could you expect the theist simply to agree that knowledge of God is "extraordinary" compared to knowledge of the natural world. This is a topic that Alvin Plantinga has discussed extensively, but one of his persistent themes is that the theist is entitled to her beliefs without having to produce arguments for them; she is entitled to them as "basic beliefs," not unlike your belief that you are looking at a computer screen right now. Again, you might disagree, and Plantinga might be wrong. But once again, in this context you can't simply presume that he's wrong. (By the way:...