In several years of debating atheism and theism, I have made an observation. Ask any believer what would convince him he was mistaken and persuade him to leave his religion and become an atheist, and if you get a response, it will almost invariably be, "Nothing - I have faith in my god." Although such people may well exist, I personally have yet to meet a theist who would acknowledge even the possibility that his belief was in error. Many theists, by their own admission, structure their beliefs so that no evidence could possibly disprove them. In short, they are closed-minded, and have been taught to be closed-minded. (For more on this, see "Thoughts in Captivity".)

In light of this, it is ironic that atheists are often accused of being the closed-minded ones. Fundamentalist proselytizers very frequently claim that we are hard-hearted, that we are dogmatic and irrational, that we reject God based on preconceived bias, and so on. Such claims result from psychological projection. Incapable of coping with the fact that there are some people who genuinely do not believe in their god, these theists simply deny that such people exist, and instead insist that everyone thinks the same way they do. Therefore, people who reach different conclusions than them must have some secret ulterior motive for not believing. This is truly ridiculous, but unfortunately, some people really believe it.

Thus, in the spirit of proving that atheists' minds are not closed, I've assembled below a list of everything I can think of that I would accept as proof that a given religion is true. Also included are things that I would accept as circumstantial evidence of a particular religion's truth and things that would not be acceptable to me as proof of anything. While I do not claim to speak for all atheists, I would confidently say that any religion that could produce one of the things from the first list would probably gain a great number of converts.

To be fair, I invite all theists to respond by preparing a list of things that they would accept as proof that atheism is true. If any theist prepares such a list, posts it on the Internet and tells me about it, I'll link to it from this page.

[Update, June 2007: This essay has been available on the internet for six years and has been discussed on numerous web forums, and this week I received what is, to my knowledge, the very first theist response to the challenge outlined above. As promised, here is the link. See also the related discussion on Daylight Atheism.]

[Update, February 2008: A second response was sent in. See discussion on Daylight Atheism.]

[Update, April 2010: Response #3. See discussion on Daylight Atheism.]

[Update, July 2010: Two further responses.]

[Update, September 2010: Response #6.]

The first category deals with things that would absolutely convince me of the truth of a particular religion. If shown any of these, I would convert on the spot.

• Verified, specific prophecies that couldn't have been contrived.
  If the Bible, for example, said, "On the first day of the first month in the year two thousand and ten, the pillars of the earth will shake and a great part of the New World will be lost to the sea," and then January 1, 2010 comes and a tremendous earthquake sends California to the bottom of the Pacific Ocean, I would become a believer. No points are awarded under any of the following conditions:
  • If the prophecy is vague, unclear or garbled (like Nostradamus' ramblings, for example). It must be detailed, specific and unambiguous in its prediction and wording.

  • If the prophecy is trivial. Anyone could predict that it will be cold next winter, or that this drought/plague/flood will eventually subside. The prophecy must predict something surprising, unlikely or unique.

  • If the prophecy is obviously contrived for other reasons. No official seer or court astrologer ever predicted that the king he worked for would be a brutal, evil tyrant who would ruin the country.

  • If the prophecy is self-fulfilling; i.e., if the mere fact of the prophecy's existence could cause people to make it come true. The Jewish people returned to their homeland in Israel just as the Bible said they would, but this isn't a genuine prediction - they did it because the Bible said they would. The predicted event can't be one that people could stage.

  • If the prophecy predicts an event that already happened and the writing of the prophecy itself can't be shown to have preceded the event.

  • If the prophecy predicts an event that already happened and the happening of that event can't be verified by independent evidence. For example, Christian apologists claim that Jesus fulfilled many Old Testament prophecies, but the authors of the New Testament obviously had access to those prophecies also; what would have prevented them from writing their story to conform to them? The extra-biblical evidence for the existence of Jesus is so scanty that it is impossible to disprove such a proposal.

  • And finally, if the prophecy is the lone success among a thousand failures. Anyone can throw prophecies against the wall until one sticks. The book or other source from which it comes must have at least a decently good record on other predictions.

  These conditions, I think, are eminently reasonable, and are only what would be expected of a true prophet with a genuine gift.

• Scientific knowledge in holy books that wasn't available at the time.
  If the Bible (or any other religious text) contained some piece of knowledge that the people of the time couldn't possibly have known but that is now known to be true, that would be highly convincing to me. A passage about the atomic theory of matter or the heliocentric solar system would be interesting, but not conclusive, since the Greeks, for example, proposed those ideas long ago independent of any claim to divine revelation. A mention of the theory of evolution would have been impressive. A reference to the germ theory of disease, or the laws of electromagnetics, would have been compelling. But what would be indisputable proof would be an elucidation of a truly modern theory of physics, such as relativity or quantum mechanics - not just something that the people of the time couldn't possibly have known of, but something so counter-intuitive that the odds against guessing at it correctly would be staggering. Just think: What if Jesus had said something like this?

  "Verily, verily, I say unto thee that thine energy is as thine mass times the speed of light multiplied unto itself."

  Of course people of the time would have been baffled, but just imagine how many souls it would have saved today. As with the prophecy item, there must be independent verification that the piece of knowledge was written in texts that existed well before it was actually discovered by science.

• Miraculous occurrences, especially if brought about through prayer.
  If cities condemned as sinful by preachers tended to explode in flames for no apparent reason, if glowing auras of holy light sometimes appeared around believers to protect them from harm, or if atheists and only atheists were regularly struck by lightning, this would be compelling proof. But it wouldn't have to be so dramatic; even minor but objectively verifiable miracles would do, especially if they could be invoked by prayer. If a hospital did a double-blind study to determine if intercessory prayer helps the sick, and it was discovered that only the patients prayed for by members of a certain religion experienced a dramatic, statistically significant increase in recovery rate, and this result could be repeated and confirmed, I would convert. This one shouldn't be so hard, especially for the Christians - after all, Jesus told them that they would be able to work miracles through prayer!

• Any direct manifestation of the divine.
  I'm not that hard to convert; I'll be happy to believe in God if he tells me to in person, as long as he does it in such a way that I could be sure that it was not a hallucination (for example, in the presence of multiple reliable witnesses, none of which are in a highly emotional or otherwise altered state). Where are the voices speaking out of burning bushes, or out of thin air when people get baptized? In Old Testament times, Moses saw God so often that he knew him on a first-name basis. Why doesn't this happen any more today?

• Aliens who believed in the exact same religion.
  And one more, though this one is just a bit off the wall. If humanity was to contact an extraterrestrial civilization, and if said extraterrestrials had a religion that was exactly like some religion on Earth, I would become a believer. (Though it would raise some interesting theological problems for Christians. Does Jesus have to travel to every planet in the universe individually, dying and being resurrected on each one?)

The second category deals with things that would not be conclusive, but that would count as circumstantial evidence. Show me one of these and I might not convert right away, but your religion will look a lot better to me.

• A genuinely flawless and consistent holy book.
  True inerrancy is, so to speak, the holy grail of theism. Almost every religion claims their scripture is perfect, but none that I know of have actually met this exacting standard; I have yet to read a holy text entirely without error or self-contradiction. A book that was free of such problems would be circumstantial evidence in favor of the religion that possessed it, but not compelling, since this is still explicable as the result of purely human forces.

• A religion without internal disputes or factions.
  It seems reasonable to expect that, if there existed a god that was interested in revealing itself to humanity and desired that we follow its commands, that god would write down whatever instructions it had to give us in a way that was only amenable to one interpretation. Thus, if a religion was true, we might expect that no factions or sects would form within it and all members of that religion would speak with one voice regarding ethical and theological issues. Why the alternative scenario should ever hold for an inspired religion is not clear. Did God intend to communicate his message clearly but failed to do so? However, since this could still be the result of human influence, it would only be circumstantial, not conclusive, evidence in favor of a given religion's truth.

• A religion whose followers have never committed or taken part in atrocities.
  If a given religion's sacred text consistently promotes peace, compassion and nonviolence, and if that religion's history reflects that fact, that religion would look much more attractive to me. Historically, almost every religion that has ever had the power to do so has persecuted those who believed differently, and I do not think it likely that a morally good deity would allow his chosen faith's good name to be smeared by evil and fallible humans.

• A religion that had a consistent record of winning its jihads and holy wars.
  Strangely, none do. One can only wonder why.

The final category deals with things that would not convince me; none of the following would persuade me to rethink my position. To date, all the evidence I have ever seen presented for any religion falls into this category.

• Speaking in tongues or other pseudo-miracles.
  To convince me, a miracle would have to be genuine, verifiable, and represent a real and inexplicable divergence from the ordinary. Anything that can be explained by peer pressure, the power of suggestion or the placebo effect does not count. Favorable coincidences or kind or courageous acts performed by human beings also do not meet this standard. (This post clearly illuminates the difference: "Biblical miracles aren't about accidents and people saying 'Whew, that was close.' Biblical miracles are people raising their hands and telling something impossible to happen, and it happens.") Seeing the Virgin Mary in a water stain or Mother Teresa in a piece of pastry is not impressive. Nor is glossolalia, not even if it really sounds like a language. And faith healing, or people being "slain in the Spirit" and toppling over, owes more to showmanship and the placebo effect used on eager-to-please individuals that have been worked up into highly excitable, suggestible states. (Now, if faith healers could restore severed limbs...)

• People's conversion stories.
  I'm not interested in the testimonials of people who converted to a religion, not even if they used to be atheists. Everyone has moments of weakness in which emotion overrides logic. Instead of telling me how fast a religion is growing, how much of a difference it's made in people's lives, or how devoted its converts are, let those converts explain what logic and evidence persuaded them to join in the first place. If they can't do this, their stories will not affect me. After all, for obvious reasons, atheists are almost never the sort of people who go along with the crowd.

• Any subjective experience.
  Saying "I know God exists because I can feel him in my heart" or something similar will not affect me. Most arguments of this sort rest on the assumption that a person cannot have a completely convincing subjective experience and be mistaken regarding its cause, but a look at the diversity of world religions easily disproves this. Christians, Jews, Muslims, Hindus, Buddhists - members of all faiths claim to have had convincing subjective experiences of the truth of that faith. Obviously, they cannot all be right. Why should an atheist accept any one of these testimonies as more valid than any other?

• The Bible Code or similar numerological feats.
  Using the same algorithms employed by the Bible Code numerologists, skeptics have been able to find assassinations and other historical events "predicted" in Moby Dick, War and Peace and other works of fiction that don't claim divine inspiration, so don't expect it to impress me.

• Creationism of any sort.
  I'm thoroughly familiar with the pseudoscience practiced by advocates of "scientific creationism" or "intelligent design". If you attempt to prove God's existence to me by listing the evidence for a young earth, more likely than not you'll be disappointed. (Though I'm always happy to debate the merits of evolution.)

Subsidiary Articles
• How Not to Convert an Atheist: Continuing the theme of the above essay, this article advises theists what arguments and tactics are likely to be ineffective at convincing an atheist to change their mind.