A question that pops up regularly is, 'what would it take to convince a non-believer to believe in god?'
In the case of Yahweh, who is supposed to be ever-present, all-powerful and the embodiment of goodness, I suppose I'd have to go with the complete and utter eradication of cancers and aids by, let's say, tomorrow (or I could be generous and say next week, even). That would be pretty convincing to me. (Btw, this condition is not mine; I hijacked it from PZ, Dawkins or some other author whose name escapes me right now).
I don't think I ask for too much.