Yes, I can prove that God does not exist, but it is also true that other people can prove that he does not. That's because "proof" in the context of such an argument is usually about whether or not God or deities are likely to exist, not whether there is some absolute logical proof of existence. (Exception: philosophical debates in the sense of scholasticism, which I am not interested in here.) We believe or don't believe because the concept of God seems credible to us, and we establish credibility on the basis of evidence. In my experience, most believers think that they have sufficient evidence to find God credible.
But how is it possible for me to prove something to exist, if someone else can prove it not to exist? Proof is always an exercise in logic. One starts with a conclusion that can be either true or false and then shows that it follows logically from a set of premises. The catch here is that the premises must themselves be true in order for the conclusion to be true. A conclusion that merely follows from premises is
valid, but not necessarily true. A valid conclusion that follows from true premises is necessarily true. That is, the proof is
sound.
Debates over the existence of God always seem to go nowhere. People on both sides of the debate are almost never persuaded to a conclusion that is opposite the one they started with. My point here is that the debate is never over the truth of the conclusion. It is almost always over the truth of one or more premises. The only way to win such a debate is to stipulate that all the premises leading to the conclusion are true.
So what is my "easy" proof that God does not exist? Right here:
- God is a disembodied spiritual agency.
- Disembodied spiritual agencies do not exist.
- Therefore, God does not exist.
Too simple? Of course it is. Most people believe in the existence of disembodied spiritual agencies, so they reject the second premise right off the bat. Very few theists will deny the first premise, although I have rarely come across some who do. It is part of Mormon doctrine, I believe, that God does have a material body, although one would need to check on that with the individual Mormon, I think.
What about the second premise? Is it true or false? I believe that it is true. All agencies, whether you want to term them "spiritual" or not, require material brains in order to exist. The evidence for my belief comes from the observation that agents cease to exist when the brains that they depend on are destroyed. We know this, because consciousness is impaired when the brain is damaged, and consciousness is a key component of volition or agency. Now don't tell me that you disagree with that belief, or we'll have to have a debate over it, before we come back to my original ironclad proof that God does not exist.
I could obviously go on, but I invite others to comment on or critique my thesis: I can easily prove that God exists, but there are others who can easily prove he does not. The argument is almost always over the soundness of the proposed proof, not the validity. So the real debate is never really over whether the conclusion is true. It is really over whether other beliefs that the conclusion depends on are true.