There's a lot of confusion about what the burden of proof actually is. Literally, the burden of proof is the requirement of an individual or group to warrant a certain epistemic position. Atheism [i]does[/i] have propositional content. You often hear atheists claim that the burden of proof lies with those making the positive claim--in this case theism--which is by all means absolutely correct but it misses the larger epistemic difference. When theists claim atheists have no [i]proof[/i] of their position, it is somewhat misleading for two reasons I) it's often conflated with the assertion "a deity (or deities) definitely do not exist and II) the only evidence you can gain for something's non-existence is negative evidence (or evidence of absence). However, that doesn't excuse atheism of [i]any[/i] burden. The negation of X is necessarily a proposition which entails its own negative evidence, or further propositions with positive evidence themselves. Saying "I don't believe X" is [i]epistemically identical[/i] to saying "X is false"; the only difference is a linguistic trick which denotes personal impositions of probability. The burden of proof for both instances is [i]identical[/i], as establishing your lack of belief is exactly the same as pragmatically establishing something's falsehood, otherwise you wouldn't lack belief in the first instance. This isn't a controversial claim to make, like, at all; it's pretty much what every atheist does in a debate when they properly counter theistic claims, but there seems to be a general consensus within the community that atheists lack a burden of proof for their propositions. The lack of evidence for something--given observation and non-confirmation of positive synthetic propositions--is evidence for the lack of it. And, indeed, positive propositions can contradict [i]other[/i] positive propositions; creationism specifically is refuted--not only by the negative evidence of atheism as an ontological claim--but the overwhelming positive evidence of evolution. We [i]should[/i] present our evidence for our positive assertions, and we should present our negative evidence to establish the probabilistic assertion of "God doesn't exist". The burden of proof is not some [i]essence[/i] of epistemology, in which propositions take part. It's a functional rule, that applies only insofar as people are willing to refuse or volunteer to uphold it. If the main claiming the invisible unicorn [i]fails[/i] to substantiate his claims, his burden of proof should be pointed out repeatedly, but there comes a point where it's worthwhile to break out the infra-red cameras and capture some negative evidence.