morriswalters wrote:What would be acceptable evidence?
Hmm... How about this: Every single prayer that is made by a Christian is granted. Always. Just like it says in the Bible. And this effect didn't work for anybody else, but as soon as you became a Christian it would work for you, too. And none of this "I prayed for my wife's health and after her surgery she got better", nonsense. I want to see some Christians casting mountains into the sea, or handing out divine smitings, or raising the dead.
While it wouldn't be conclusive evidence, if a species of aliens visited us, and were Muslims who read the Koran (in Arabic, of course) and worshiped Allah, that would be pretty damn impressive evidence for Islam being the way to go.
God appearing bodily to every single person on Earth, speaking to them in their own language and calling them by name wouldn't be a bad start. Especially if he hung around for a few years afterward.
While it's a little late for it now, if any of the religious texts contained specific, correct, scientific information that could not have possibly been available at the time, that would be pretty impressive evidence. Say, if the Bible had included a scale diagram of the Milky Way galaxy, or had described how a cell worked, or mentioned E=mc^2. Or, hell, said that diseases were caused by microscopic organisms that could be killed by proper sanitation.
Strictly speaking, none of these pieces of data are, in fact, sufficient to establish that there is a God as described by most religious. None of these would rule the possibility, for example, that the event is caused by an extremely advanced alien civilization that just wants to mess with us.