would you guys stop with the patronizing sarcasm please?
If somebody wants somebody else to believe something, especially something that's unbelievable by its very nature, the burden of proof is always going to be on the one making the claims.
Healthy skepticism is probably the most intelligent position to take regarding claims of extraordinary miraculous events.
*in my best mocking voice* "considering how important this claim might be..."
If some God was really writing things in the sky, then that would obviously be the most important event on the planet.
Of course, the problem is establishing that some God was really doing that. I think that given the realities of human psychology, that imagination, self-delusion and conceivably even psychopathology are more likely than divine miracles to be explanations for these kinds of reports.
I happen to personally know a guy who often hears voices speaking inside his walls, talking about him. Nobody else has ever heard those voices.
It's sad, but it happens. In fact, it seems to happen a lot more frequently than gods writing Arabic across the sky. And that in turn suggests that the explanation for miraculous words seeming to appear in the sky are more likely to be psychological than theological.
But like Spidergoat says, if these words in the sky were visible to other people too, visible to everyone (even to non-Muslims) who looked up at the sky, and if they could be captured on cameras and recording instruments, then the odds might start to shift towards some other kind of explanation.