What evidence would it take for an atheist to believe in a god?
This question comes up often enough to be worth a lengthy response, and, in short, my reply is that such evidence is impossible. I claim that any event that should ever occur to be observed by man that could suggest the existence of a deity will always, in every case, and indefinitely never amount to sufficient evidence for such an existence through no obstinance or arrogance of the atheist, but through mere logic and reason. My argument is as follows.
First, I'd like to draw attention, yet again, to the heroic (arguable) David Hume. Concerning miracles, Hume stipulated that in order for a miracle to be accepted as having occurred, the falsehood of the testimony would have to be more miraculous than the miracle itself. After all, the lesser 'miracle' would be more likely to have occurred, just as it is more likely that I am typing this text rather than it just appearing without any direct or indirect user input. To quote Hume: "When anyone tells me, that he saw a dead man restored to life, I immediately consider with myself, whether it be more probable, that this person should either deceive or be deceived, or that the fact, which he relates, should really have happened. I weigh the one miracle against the other; and according to the superiority, which I discover, I pronounce my decision, and always reject the greater miracle. If the falsehood of his testimony would be more miraculous, than the event which he relates; then, and not till then, can he pretend to command my belief or opinion." This fairly accurate worded phrasing puts the nail in the coffin concerning that which would be required for a testimony of a miracle to be accepted as factual. We then have to ask ourselves how such a falsehood of testimony could ever be more miraculous than the miracle itself.
*On a quick side note, I can foresee the argument that my terminology only suggests that I will accept the more probable event, and that while winning the lotto is less likely than not winning the lotto, both are possible outcomes, and thus I erroneously equivocate the less likely (or improbable) with impossible. However, before you can suggest something to be possible it has to have been given evidence to support the claim. Miracles have yet to be shown possible and thus I do not run into the obstacle just described. Winning the lottery is indeed possible and has been proven so. Moreover, the analogy is a descriptor of what happened before the lottery numbers were picked, not after. After the lottery numbers are known, it's either impossible that I've won if I haven't, or impossible that I haven't won if I did. One merely needs to look at the numbers and submit it to the lottery board to find out. The claimed miracles in question have already occurred and their validity of being called a miracle is in question, not the perception that it has occurred.*
Lyre birds are capable of mimicking the most unusual sounds, including the sound of a chainsaw cutting through a trunk of a tree. We constantly deceive children into thinking there's a Santa Claus. Mirages occur to people travelling through a desert. Derren Brown can use his powers of deception to convert an entire room to believe there might be a deity, or to convince people that a losing race ticket is a winning one.
Hallucinations will form to those who are mentally ill or extremely physically sick.
People actually believe that Barak Obama is a Muslim and a terrorist, and the Saddam Hussein actually had WMD's. Hell, you've probably even thought that it was your left hand that was shaving your beard, looking in the mirror.
Pick up any psychology book and you're bound to find numerous instances defining some sort of mental disorder which creates illusions. Are aliens really infiltrating our minds? Is the government wire-tapping my phone line? Am I the next Messiah? Why do the pink elephants steal my pillow at night? When will Nessy wakeup? Who is Bigfoot? We are in constant reminder of the ability of people to be deceived, and yet we never give them any credit to their illusions/delusions.
On all levels, and in every corner of the globe, people are deceived, have been deceived, and will continue to be deceived. But what we have never witnessed anywhere near as much is the laws of nature to be suspended. Even if the miracles claimed by the various religions were indeed to have occurred, they are far outweighed by the instances of deception that is continually being put to use for bad and good intentions, and sometimes unintentionally.
But let us assume, for the moment, that by some 'miracle' the likelihood of deception was actually outweighed by the miracle itself. That what we saw really did happen and what happened went against the grain or was unknown of our current knowledge of the natural laws of the universe.
Do we really attribute it to miraculous circumstances?
When scientists discovered that light bent around a planet, did we think it was a miracle that it went against Newton's law of gravity? When the animist of old witnessed lightning, something they certainly didn't understand the physics of, did it command miracle status? Is birth still considered a miracle after biologists have dissected the process of specie fertilization; that of sperm and egg, meiosis, and mitosis?
In any instance in history where there has been a verifiable observed seeming suspension of natural laws, it is not the event that is deemed miraculous; it is our ignorance of the natural laws. Never do we (or ought we) assume that which we don't understand a miracle. Especially since the introduction of quantum mechanics, even some of the most improbable and counter-intuitive events could conceivably occur by no suspension of what is natural. It will always be more likely that we will yet discover what happened by the natural order of the universe than for such an event to actually have ignored the true natural order.
Lightning, medicine, gravity, stars, chemistry, etc were all once thought miraculous or magical and since then there has been substantial proof that deeming such things as miraculous is to admit our ignorance of natural laws, not of such events being actually miraculous. And since all of our current knowledge of the universe has been preceded by our ignorance of it, it will always undeniably be far, far more likely that we as of yet do not understand how such an event has occurred than for such an event to be truly miraculous.
That is why no evidence will ever suffice for the proof that miracles happen. That is why the falsehood of the testimony and our ignorance of the natural world will always be far less miraculous than the miracle itself, and thus not command our belief..
And that is why I, as a rational human being, will always be an atheist.
by Watts of AvC