As always the barmaid hits the nail on the head. She tells Jesus and Mo, "You cannot escape the fact that when you say 'God says X' what you are actually saying is 'I say God says X.'"
Believers of various religions tell us in so many words that "deity Y said/did X." As the barmaid explains, the statement is elliptic and leaves out important details: "My imam/rabbi/guru/priest/pastor says...", "Book B says...", "I say..." In short the statement "deity Y said/did X" is merely a claim. Without empirical substantiation it is irrational to believe in it not least because the existence of the claimed entity has not even been shown to be true.
Logically, epistemologically speaking, any statement in the form of "entity E said/did X" is presumptuous unless E is a phenomenon that is already known to be true/real. The antecedent and implicit premise is "E exists." So unless E is in fact known to exist and has been reasonably shown to exist, to be true and real, immediately telling the reader/audience "E said/did X" is misleading.
An example to illustrate: "E performed surgery on author Daniel Dennett." Now replace E with one of the following:
1. Michael Hopkins, M.D.
2. Ahura Mazda (god of the Zoroastrians)
3. Diktab, a doctor from the planet Woptwam located 3 billion light years from Earth.
Clearly #1 deserves the least skepticism. We know that humans exist. We know that humans who have medical degrees have in fact performed surgery. #2 and 3, however, deserve utmost skepticism, and should not be believed in. There is no evidence that Ahura Mazda exists. There is yet no evidence that any extraterrestrial lifeform exists. And of course there is no evidence that there exists the said planet at the specified location, and one that has a population of organisms that have the intelligence and technology for surgery.
#3 is instructive. The more specific the claim--the more details there are in it--the more premises are being offered, the lesser the probability of the claim being true, and the riskier it is for the one making the claim. Thus in #3 the claims include a planet, a given distance, a sentient being (and even perhaps a range of species and their evolutionary lineage), a nonhuman who has medical expertise and knowledge of human anatomy and physiology, as well as the implicit claim that this being was somehow able to travel the 3 billion light year distance (either physically or otherwise) to operate on Dan. That's a lot of claims packed into it.
Whenever an extraordinary claim comes up, we need to automatically ask, How do you know it's true? Just as well we need to ask ourselves what we haven't been told, what the implicit premises are. Many times once we expose these hidden premises the claim immediately falls flat on its face simply because these premises have yet to be shown to be true. Thus with any claim that deity Y commanded or did X, by merely revealing the fact that Y is not yet known to be true, the entire claim comes crashing to the ground.