If Russia attacks Israel with just about every weapon it has, but is defeated by fire from the sky. Something the Israelis could not produce themselves, than I would be on my way to believing.
God appearing before me would help too. Of course I would have some tests for him. Like not speaking at all and having him read my mind. Maybe a little time travel and finally being able to create something out of thin air. Nothing big LOL
Of course someone coming around the corner right now and giving a me a suitcase with a few million dollars in it would convert me on the spot. Heck even a $20 might do it right now.
(Darn! I Knew it wouldn't work!)
Too often I hear the response, well you wouldn't believe even if god did show up in front of you. To that I say, try me.