DeadChannel

That's not how logic works because there is a difference between positive and negative claims. Saying that you don't believe in something is only a declaration that you have no been presented with sufficient evidence to do away with your doubts -- a totally reasonable position when no evidence at all has been presented. Further, there is a difference between the sentences "I do not believe in X" and "I believe that there is no X". The later requires a justification, the former needs none unless a justification is given for the existence of X.

For instance, I do not believe in the giant plush orang-utan suction cupped to the back of Jupiter. I'm totally justified in my lack of belief in this entity despite the fact that I've never been to Jupiter, because the burden of proof is on the maker of extraordinary claims.

This exists for a reason. The natural conclusion of your line of thinking is silly and absurd: we ought to take every claim, and indeed, every possible metaphysical claim seriously. Since no one has time for this, the only reasonable method of determining what is true and what is false is expecting justifications from those making claims, not the other way around.