Okay. Atheists still don't have to prove that god doesn't exist.
Yes they do. If you make any claim of any kind, you have to back it up. That's the way claims work.
That only applies when you're disputing something that is already accepted as proven. Since a God hasn't been proven in the first place, the way I see it that's where the burden of proof lies, if anywhere. You don't need to disprove something that can't be proven. In fact, you can't, which makes it a futile argument in both directions.
Not that I'm saying theists need to prove anything to anyone. I accept faith as a perfectly valid reason to believe, but I don't accept it as proof that needs to be disputed to believe otherwise either.
I could easily reverse the statement and say, "Since the nonexistence of God hasn't been proven in the first place, that's where the burden of proof lies."
Burden of proof lies with the person making a claim. Whether that claim is for existence of something or for nonexistence of something is irrelevant to the fact that a claim needs to be backed up.
At the intersection of Main Street and Cornell Place in South Park, Colorado, there is a large rock. Or perhaps there isn't. If you ask Jimmy, he'll tell you the rock is there. It's invisible, and he's never heard anybody else talking about it, but he knows it's there. He makes sure not to drive through that particular intersection, because he doesn't want to hit the rock. He doesn't even walk near that intersection, because he's not sure how big the rock is and he doesn't want to stub his toe.
Mark, however, doesn't think the rock is there. The thought has never crossed his mind, because he goes through that intersection daily and has never encountered so much as a small bump.
One day Jimmy met Mark and Jimmy brought up the rock. Mark thought the claim that there was a large rock at the intersection of Main and Cornell was outrageous. Mark contradicted Jimmy's claim, saying that there was no rock at that intersection; Jimmy said he knows the rock is there, so maybe only people who believe in the rock will feel it.
On that day, Jimmy had to provide evidence for his claim, because
to endorse something that is outrageous and unprovable requires some evidence. Jimmy takes the long way to work every day because he wants to avoid the rock; surely he has some logical explanation for this.
Failing to support this belief with some evidence is at best naivety and at worst insanity.
Mark, however, did not have to provide any evidence for his claim.
Not believing in the rock is a statement of no difference. Mark has not yet encountered any evidence that there may be a large, invisible rock at the intersection of Main and Cornell, so it seems unusual to make Mark prove that there is no rock there.
Mark does not need to prove there is no invisible rock at the corner because if he did, he would then have to prove that there is no invisible turtle or no invisible can of cream soda, etc. Mark is justified in not believing in a rock he has no reason to believe in.
You make these same kinds of judgments every day -- for example, when you walk down the street in your hometown, you are never worried about there being invisible obstacles. With each step forward, you make a judgment about whether something invisible is there -- you take a stance on the invisible obstacle issue. If you did have to rigorously prove the nonexistence of any number of invisible obstacles, life would be extremely difficult.
Unlike with belief in the rock, disbelief in the rock without evidence is not a mark of naivety or insanity. However, if Jimmy offered some incontrovertible evidence that the rock did exist, and Mark still ran through that intersection with reckless abandon, the burden of proof would fall to Mark to explain why he is making his claim. This is because his claim contradicts something that has been rigorously proven, and is therefore outrageous.