It’s heard on the lips of of some atheists that they, unlike us theists, don’t bear the burden of proof in the question of God’s existence because they merely lack the belief in God. The theists bear the burden of proof, however, because they make the claim that God exists. I agree with this reasoning only in that it affirms that the person making a claim bears the burden of proof. However, the atheist, just like the theist, makes a claim about the existence (or non-existence) of God and therefore equally bears the burden of proof with the theist. “But they don’t”, it may be heard, “they lack the belief in God’s existence” so they aren’t making a claim and therefore don’t bear any burden.

But this is a clear misstatement of the atheist’s position. If this were the whole picture, then the atheist and the agnostic are literally indistinguishable! This is clearly wrong. Rather we should ask, “what do you believe about the statement ‘God doesn’t exist’?”. If the atheist affirms the statement then he’s making a claim (namely, that God doesn’t exist) and therefore bears the burden; if he lacks belief in the statement, then he’s not an atheist, he’s a [weak] agnostic! If he neither believes that God exists nor that God doesn’t exist, then of course he doesn’t bear the burden, since he’s making no truth claim! But again, this isn’t the atheist’s position, this is the agnostic’s position. The atheist, like the theist, makes a truth claim and, along with the theist, bears the burden of proof for his claim.

Furthermore, if we could just restate a position from “belief that God doesn’t exist” to “the lack of belief God exists” and in doing so simply remove the burden of proof, what’s to stop the theist from restating his position from “belief that God does exist” to “the lack of belief that God doesn’t exist” and similarly remove the burden?

But as I’ve already pointed out, this move simply conflates the view with agnosticism, and so is untenable.

One defence I’ve seen for the atheist’s claim that they don’t bear the burden of proof is a flawed analogy: just like in the courtroom the defendant is innocent until proven guilty, so we should hold God doesn’t exist until it can be shown he does. Now this is flawed on two counts. Firstly, why think that the defendant is analogous to the atheist’s position and not the theist or the agnostic? In fact as I’ve shown above, it seems to fit best with the agnostic if anything. Secondly, it seems there’s been a misunderstanding in the intentions of the legal system. We don’t assume the defendant’s innocent until proven guilty because it’s the perfectly logical thing to do. Rather it’s because we figure it’s better to let a guilty man go free than punish an innocent man. We’re purposefully illogical because we don’t want the shortcomings of the legal system to unfairly punish an innocent man. So the courtroom is not an adequate analogy to question of God’s existence, since we’re trying to be logical here.

Another line of defence I think the atheist could take is to claim that since there’s no evidence for God’s existence, we should assume he doesn’t exist. But this is just misguided and we can see this by considering three points. Firstly, absence of evidence is evidence of absence only if we would expect there to be that evidence in the first place. So just because we don’t see any evidence for God’s existence, doesn’t entitle us to infer that he doesn’t, in fact, exist unless we have some reason to think he would make himself known in the first place. But this is an extremely presumptuous claim on the atheists part; a claim that he would need to (and can’t) defend. Secondly, I’m sure the theist would claim that there is evidence for God’s existence (whether it be one of the many theistic arguments, or (if they’re a Christian) the evidence of the reliability of the life, teachings and resurrection of Jesus Christ) and the atheist is being rather unfair in simply assuming otherwise. Thirdly, the question of evidence usually comes after the question of burden, and so the atheist is possibly jumping the gun here a bit (this is, admittedly a weaker reason than the first two).

Yet another line of defence that could be taken is to whip out Occam’s Razor: because atheism posits one less entity to explain reality it should get the benefit of the doubt. Again, the atheist’s move has problems. Firstly, of all the worldviews, atheism doesn’t actually posit the least amount of entities. Pantheism (in which only God exists) or solipsism (in which only I exist, so I effectively become God) posit only a single entity and are therefore much simpler than atheism. Secondly, this defence just assumes that all theistic arguments are invalid, since they show that God’s existence is required to explain the existence of the universe, objective morals, fine-tuning, consciousness, logic, the validity of reasoning and so on. So it’s just simple question-begging prior to any considerations of theistic arguments. Thirdly, it seems wholly arbitrary to claim one view has priority over another purely on the basis of simplicity unless there’s some reason to think that reality should be more simple than not. Now under theism, at least, we have some plausible reason to think that reality might be simpler (the assumption that God, the designer, designed it simply). But atheism gives us no reason for thinking so. So the appeal to Occam’s Razor is just groundless. Fourthly, Occam’s Razor is merely an explanation guide. So our conclusion could at most be that God is not needed to explain the universe. Moving from that to the claim that God doesn’t, in fact, exist is to make the same move as the last point (absence of evidence to evidence of absence), which I think we’ve already adequately responded to. Not needing to posit him as an explanation, is a case of there not being any evidence for him.

The final line of defence would be a reductio ad absurdum of the conclusion of my above reasoning. After all, if my reasoning is sound then we should accept that the tooth fairy, or Father Christmas, or unicorns exist. And to this I respond, “not so fast!”. Nowhere have I said that theism is true because atheism bears the burden of proof. No, I’ve just said that atheism (as well as theism) bears the burden of proof: that we can’t just assume it without some reason, that it’s not the default position. Why should we assume these things don’t exist without some reason? You can’t just say, “because they originate from stories” since this would be the genetic fallacy. So for what reason might we disbelieve the existence of them? Well, each of these comes in the context of a story. Father Christmas, for example, is supposed to deliver presents to every child on Christmas day and he’s supposed to live in the North Pole. But we know no-one lives in the North Pole and we can stay up on a Christmas evening to see that no big bearded man comes to deliver presents. Now we have absence of evidence where we would expect evidence, and so we have evidence of absence. Same goes for the tooth fairy. As for unicorns, we would expect to have found something like that if it naturally occurs on earth, but we haven’t. Also, the theist can assert something like “God would be somewhat consistent in creation and not create magical creatures” to give prima facie evidence against the existence of unicorns.

I can’t think of any other reason for the atheist to defend his position. So, just like the theist, it seems the atheist also bears the burden of proof. The agnostic (the one that neither claims that God does or doesn’t exist) bears no burden since he doesn’t make any truth claim.

An even longer (and better) answer than this one is here.