For the record, I consider myself to be a skeptical agnostic.

Consider a Universe in which God does not exist.
Those who wish to disprove the existence of God claim that we live in such a universe.

Now consider a Universe in which God exists, but He* chooses not to intervene in any way perceptible to man.
The two universes are, by definition, indistinguishable, and thus, there is no way to prove that we live in the former.

Thus, there is no way to prove the non-existence of God.

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*The capitalized singular masculine pronoun 'He', generally associated with the Christian God, is used for convenience. This argument applies to any omnipotent, omnisicent being.

Which matters not. Since we are presumably speaking of rational debate, this means the burden of proof is on the one who makes the claim. Meaning, of course, one must point to evidence that some sort of god exists. (Reasons for why this is so can be found easily enough in any textbook on debating, if not Everything itself.)

This is not to say the above is untrue, but simply irrelevant. Nor is it to imply I deny the possibility of a god. Although if it does nothing, I would say that a difference that makes no difference is no difference.

In response to JustSomeGuy, three things:

1. An "omnipotent, omniscient being" (the usual working definition of "god", as far as I can tell) is logically impossible in the same way as a square circle or an invisible pink unicorn. If you maintain that a deity with these characteristics can exist, you're logically compelled to accept the possiblity that a square circle exists. Are you willing to do that?

2. What exactly do you mean by "in any way perceptible to man"? Can you give an example of something that can be said to be objectively real, yet could never possibly be perceived by a mortal in our universe? Perhaps there is a "meta-universe" in which this deity exists; this meta-universe would completely contain the universe we inhabit, as well as a whole host of other things which never interact with our universe. Maybe the rules of logic are different there, such that things which are both all green and all red can exist. However, in this scenario I would maintain that it is still correct to say that these meta-level things do not exist in our universe. Would you disagree?

3. Maybe you mean that a super-powerful entity could exist, and that this entity could have intentionally set the universe up in such a way that every aspect of the universe indicates to a rational agent that the super-powerful entity does not exist. If this is what you mean, then I'm guessing that the spelling mistake you refer to at the beginning of your WU is that you wrote "God" when you meant "anything". In any event, I don't think that this kind of entity is what anyone means when they say "God".

The fundamental answer to this is Ockham's razor: don't assume concepts you don't need. Or, even more fundamentally: concepts are only 'placeholders' to express facts about reality, so it is fundamentally unsanitary thinking to assume a concept as given and reason about its existence afterwards. Every meaningful concept reflects observations in reality.

So if God does not manifest himself in reality, God is an ill-defined term (somewhat comparable to Bertrand Russell's the present king of France) and anything you want to say about it is meaningless.

Another way of putting this: existence means manifestation in reality. If God doesn't manifest himself in reality, he does not exist by the very meaning of the word. Again, this is only true when you look upon existence with a scientific frame of mind.

skid: Regardless of where the burden of proof lies, in JustSomeGuy's own words, "there is no way to prove the non-existence of God." That's different from the node title, which claims that "the existence of God cannot be disproven." It can be disproved (if it can be "proven" in the first place) but as JSG said, God can't be proven to not exist. That's what this node is really about.

Lord Bear: It's not limited to the human system. An omnipotent being can make eirself undetectable to anyone, even a being of "higher evolution," assuming that being isn't itself omnipotent. Perhaps there can't be multiple omnipotent beings, but that's a whole 'nother cup o' beans.

However, JSG's argument is fine, it only applies to the nodescript onmiscient omnipotent being. Most Christians like to throw in omnibenevolent, which makes for a new problem, and may allow for disproof of this good god.

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(I'm a skeptic (Epistemologically speaking) so I don't believe anything can be proven beyond all doubt. Descartes destroyed my illusion of knowledge and failed miserably in his awful attempt to recreate it.)

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Some years later: I'd make this writeup not suck, but I'm too lazy. For now I'll just point out that the verificationist would define JustSomeGuy's god as non-existent.