Now that you mention it, I'm not entirely convinced it is a fully coherent belief in its own right, more of a lack of wanting to enter the debate or a subcategory of atheism.

Shall we try it with unicorns? Unicorn believer says they saw a unicorn.

Atheist viewpoint would say something along the lines of "To persuade me they exist I'd need to see one in the flesh or at the very least a full anatomical breakdown of how their magical properties work with corroboration from other unicorn enthusiasts."

The agnostic standpoint is what exactly? "We can't know whether unicorns exist or not so there's no point discussing it."?