> Merely saying that consciousness is a product of the brain is like proving dark matter by saying it's a product of the universe.

This statement is nonsense. The presence or absence of consciousness could be empirically verified and experimentally tested. The presence or absence of dark matter could not be empirically verified because the concept which is referenced by this pair of words belongs to the category of abstract ideas.

Notice, that consciousness is not an abstract idea, it belong to the category of biological processes. You have here a logical error of assuming existence of an abstract concept, which neither could be empirically verified nor experimentally tested.

There is a subtle difference between a product of the physical brain and a product of group-thinking or sectarian beliefs. While the concepts which form the basis of this or that system of beliefs are certainly exist inside the consciousness of the individual believers and certainly are presented in their shared vocabulary, the phenomena which these concepts presumably accurately and completely capture does not exist anywhere in the universe.