The burden of proof rests with whoever is making a particular argument, particularly those arguing against an accepted norm.
If an atheist comes here to tell us how stupid we are because everybody knows there's no God, then it's up to the atheist to show evidence that there is no God, just as if we went to Internet Infidels it would be up to us to demonstrate evidence for our claims.
Of course, the atheist will say that that's a negative claim and you can't prove a negative. There are two small problems with this.
The first is that it isn't a negative statement. "There is no evidence of a God" would be a negative statement. "There is no God" is not.
The second is that, contrary to popular opinion, you can prove a negative claim. Although, in all fairness, I don't like to use words like "prove" because "proof" is largely subjective. The best you really can do is to provide evidence in a well reasoned argument and leave the "proof" up to the individual to decide.