BTS: For some, if they can't submit an event or experience to repeatable, verifiable, experimentation, then the answer is not even then. Or, they would create a naturalistic explanation. If it is an event witnessed by many people, they will invoke some form of mass hallucination to explain it. In other words, anything can be explained away, if you don't want to believe it. When all you grok is the hammer of naturalism, every supernatural event looks like a nail. If God can't be put under a microscope, or prodded like a specimen, then he does not exist. For those that believe, no miracles are needed. For those that don't, no miracle will suffice.
Oh come on for christ sake! The Big Bang, all major events in evolution and yesterday is not someone a person you describe would believe in! are you really, really sure that kind of belief system applies to anyone but the clinically insane?
And mass hallucination my ass. If a 10m^3 block of solid diamond with the bible written on it appeared on times square tomorrow THAT would be a miracle that would turn me into a believer overnight because God would be the most natural explanation - sure, aliens could have done it, but that seem darn far fetched.
And atheists does not suffer from some disease they can be 'cured' from, its an extremely arrogant attitude. I invite any biblical litteralists to start a thread about the scientific case for the flood and see whos belief system is most founded on evidence ;-)