Many people think that according to big bang cosmology, first there was empty space, then there was an explosion in the middle of the emptiness, and now all the galaxies are flying away from that original point in space.
If they discuss this with a physicist, they will be told no, in the big bang theory, space is filled with matter from the beginning, it's space itself that is expanding, and so on. See e.g. this Phys.SE post. And then, if the conversation gets that far, all those unexpected details will be explained as making sense in general relativity.
This is fine as a description of what physicists actually think. But it doesn't address what's wrong with the "naive big bang idea" as a theory in itself.
So I have two questions:
What is the most sophisticated realization of the naive big bang idea, as a cosmological theory?
What are the best arguments against the viability of the naive big bang idea?