You said: A rational deity ought to at least insure that the punishment fits the crime. So because one chick decided to take a bite of a forbidden apple, all later generations are condemned to die—in many cases, in great pain and suffering. Sorry, that's a disproportionate punishment and, as such, it offends the rational mind.The punishment was announced prior to the "crime." The "chick" was forewarned as to what would happen. That's what happens when you are created in the image of God-- there are consequences. Whyy do you blame God for something He didn't do?
Let's say you forbid your children—who don't yet grasp the difference between good and evil and who don't know that there are evil forces in the world who might induce them to do wrong—from swallowing pills which, if ingested, will teach them the difference between good and evil. Let's say you warn them that if they ingest the pills, you'll personally see to it that they ultimately die horrible deaths. Let's say that your kids go ahead and ingest the pills. Would you carry out your threatened punishment?
If so, I'd say that you'd acted justly (because of the warning), but unmercifully and also irrationally (on any rational scale I'm capable of grasping, the 'crime' of learning the difference between good and evil doesn't merit the punishment of horrible death).
More generally, the notion of a vengeful deity is something of an oxymoron. Tout comprendre, c'est tout pardonner.
You said (in part): (on any rational scale I'm capable of grasping, the 'crime' of learning the difference between good and evil doesn't merit the punishment of horrible death).
I am prepared to admit I don't know all that God knows, or even all about God. You and I may not be capable of grasping the "rational scale" that God employs.
As I read Genesis, God did not say that anyone would die a "horrible" death, but certainly people do die such deaths. Do we blame God for these deaths? If I am advised not to judge other humans (and I try not to do so), I will certainly avoid judging God. I have said on other posts that there is little or no good in this world that occurs without evil, bad, discomfort or pain. Generosity, cures for illness, courage, comfort, sacrifice, and all other good that I can think of exist only in the face of evil or less than ideal circumstances.
I believe we usually look at God from our human perspective, and that is natural--but it may not give us the true perspective. God, I suppose, could have pre-programmed us for obedience, much as He did the animals, but I believe God wanted more from us. He gave us the freedom to obey Him or not, so that when we DID obey and honor Him, that obedience and honor had value. When I make my children clean their rooms, they do it... because I said so. Occasionally, though, they clean the room on their own, just to please me. On these occasions I feel pride in them. The same task is more rewarding to me, and to them.
Sorry for the extended response, but there you go, for what it is worth.