I'm unsure if my opponent knows what the burden of proof actually means. Suppose my friend claims there's a omniscient, omnipresent, omnipotent being outside of my room. If I don't hold the burden of proof, then I can confidently deny that proposition if evidence hasn't been provided to prove the opposite, therefore, my position is rational. And Id also disagree with you saying that if atheism means "no belief," then its rational in the same trivial way a rock is. Atheism is a lack of belief in a metaphysical deity that can affect your life considerably. Compared to that, a rock is essentially nothing. Your claim needs to be justified and id prefer it if we could hold onto the topic rather than just rebranding my argument and attacking it from that new weak side.