We had a 14 page thread last summer (Religion in Modern America
) were all your concerns are addressed. Most of it consisted of a couple people pointing out that an institution resembling religion is important because it motivates people and another couple repeatedly telling stories like yours above thinking they were performing a reduction to absurdity when really they just didn't understand the topic of conversation.
(cue: "No I do understand and it's bullshit I tell you!!! Bullshit!!!")
They made the exact same arguments so you're not setting anyone straight, just so you know. If you mention burden of proof or positivism I'm gonna snap.
...Similarly, I'm going to propose that pixie dust gives my toaster the motivation to pop, lunar beams cause my food to heat in the microwave and 8 feet long invisible tarantulas caused my parents to fornicate.
See, this story is useless not because it's not true but because it doesn't help anyone understand anything. You made it up to sound implausible and stupid not to motivate good behavior as deemed by a cultural standard.
There are different strata of humanity and each one needs to have the world explained to them in a different way. The truly enlightened, who do not actually exist, would not need symbols or allegories to help them understand the world, they need no God Concept. On the other end, there are the dumbest and/or least philoposhical who need rules like "Thou shalt not lie" explained to them by saying "You'll go to hell if you lie."
Second, why apply a literal criticism to a metaphorical story? Do you do that every time you read fiction? Do you think Tolkien is stupid because there is no such thing as magic or dragons in reality? Then why do it to the bible?
To anticipate a question: Why are people told the bible contains literal truth? because that's how you get them to heed the wisdom contained in it.
These same ideas are the similar to those espoused by the Nazis which coerced millions of idiotic sheep into committing the holocaust, going to war and dying pointlessly for imperial gains.
But these ideas did
motivate them. They're apparently the only way to motivate the masses. And if they can motivate them for purposes we deem bad, then they can be used for purposes we deem good. What do you want to do, not have a society? The people need direction and it needs to be delivered in a way effective for the audience.
4. Religion as an abstracted concept (that is a group devotion to a set of beliefs) is just part of human nature and if we don't have an cultural institution to fill that need, what will?
5. You tell from the length of this post that the issue is more complicated than just applying Occam's razor to each myth, isolated from context. And that might be where you start to go wrong (I think, anyways) is that you remove the concept of religion from the context of humanity and criticize it from what it is in itself. Can anything we make stand up to that?