Jerry Coyne challenges PZ Myers:
Both Greta Christina and I have written about what sort of evidence would convince us of the existence of a divine celestial being. But maybe P.Z. is a tougher nut to crack. So here’s a challenge to him:
Suppose that you, P.Z., were present at the following events, and they were also witnessed by lots of other skeptical eyewitnesses and, importantly, documented on film: A bright light appears in the heavens and, supported by wingéd angels, a being clad in white robe and sandals descends onto the UMM quad from the sky, accompanied by a pack of apostles with the same names given in the Bible. Loud heavenly music is heard everywhere, with the blaring of trumps. The being, who describes himself as Jesus, puts his hand atop your head, P.Z., and suddenly your arms are turned into tentacles. As you flail about with your new appendages, Jesus asks, “Now do you believe in me?” Another touch on the head and the tentacles disappear and your arms return. Jesus and his pack then repair to the Mayo clinic and, also on film, heal a bunch of amputees (who remain permanently arméd and leggéd after Jesus’s departure). After a while Jesus and his minions, supported by angels, ascend back into the sky with another chorus of music. The heavens swiftly darken, there is thunder, and a single lightning bolt strikes P.Z.’s front yard. Then, just as suddenly, the heavens clear.
Now you can say that this is just a big magic stunt, but there’s a lot of documentation—all those healed amputees, for instance. Even using Hume’s criterion, isn’t it more parsimonious to say that there’s a God (and a Christian one, given the presence of Jesus!) rather than to assert that it was all an elaborate, hard-to-fathom magic trick or the concatenation of many enigmatic natural forces?
More here. And PZ Myers responds with “Eight reasons you won't persuade me to believe in a god”:
I have been challenged by Jerry Coyne, who is unconvinced by my argument that there is no evidence that could convince me of the existence of god. Fair enough, I shall repeat it and expand upon it.
The question “Is there a god?” is a bad question. It's incoherent and undefined; “god” is a perpetually plastic concept that promoters twist to evade evaluation. If the whole question is nebulous noise, how can any answer be acceptable? The only way to win is by not playing the game.
There's a certain unfairness in the evidence postulated for god. I used the example of a 900 foot tall Jesus appearing on earth; there is no religion (other than the addled hallucinations of Oral Roberts) that ever proposes such a thing, so such a being would not prove the existence of any prior concept of god, and will even contradict many religions. It's rather like proposing a crocoduck as a test of evolution.