First let me say that I've enjoyed reading both this thread and the other one on the free will defense, as I think your criticisms are cogently expressed. I've been thinking about similar things recently, too. My problem with the Genesis account is that the history of life on the planet as we now understand it rubbishes God's boast that it was created "very good" prior to the fall. The world has always ever been fallen, that is to say, has always contained horrendous suffering, evil, and death. For hundreds of millions of years, a timescale so vast it can't even be properly imagined, various living organisms have preyed on each other, fought each other, starved, become sick, or suffocated to death in sink holes, bogs, and under volcanic ash, which preserved their skeletal remains we now gawk at in museums. These processes continue today as well. Just look around or watch any nature documentary.
Creation has never been good, unless one is so callous as to call the processes just described as "good." Some theologians do this. They say the lion eating the lamb is good for the lion but bad for the lamb. Therefore the lion does no wrong. Yet to admit that the bad existed alongside the good still means that the pre-fallen world was not good, or not wholly so. So what accounts for this state of affairs? To answer this question with "the fall" would have to mean that it affected two temporal dimensions: the past and the future, not just the future, as traditionally believed and as implied in Genesis. If granted, whatever it means, we must then ask what accounts for the fall. The traditional answer is that our ancestors were tempted by Satan to rebel. But now, having pushed back the problem of evil to Satan, we seem to have reached a dead end. In other words, if the natural evil in the world is due to the corrupting influence of Satan and his minions, both pre and post-fall, and moral evil is due to the choice of human beings tempted by Satan to do evil, then we have satisfactorily explained the problem of evil with respect to the world. However, we are still left with accounting for Lucifer's fall. It appears as a dead end because there isn't a second Satan who tempted the first to rebel. One fall explains the other, but the first, the fall of the angels, seems to admit of no good explanation.
If the answer is "pride," we can ask: why was Lucifer created to be susceptible to pride? Why also was he created at all, since his creation precipitated the whole tragic history just enumerated? Indeed, why did God create anything at all? Did he have to? If God had a reason to create, then he was determined to do so by that reason and so did not do so freely (or at least isn't free in one sense of the word). If God created freely, then he had no reason to do so, and so is capricious, or seemingly capricious. Perhaps, as you said in the other thread, the only answer to these questions is what we find in Job. But as you also said, this leaves one deeply unsatisfied, as it sounds like a cop out. We might then consider the following mottos:
intellectus quaerens fidem et fides quarens intellectum. The former, "understanding seeking faith" is perhaps what you are doing now, inasmuch as you are seeking to believe but find there are theoretical difficulties in doing so due to your understanding of what Christianity claims. So maybe you ought to adopt the latter motto first, i.e. "faith seeking understanding," such that you believe in order that you might understand. Understand what? The meaning of problems like the one you have addressed above. It could be that if you remain on the outside looking in, the problem will never be understood. Perhaps its solution isn't strictly communicable in the form of an air tight syllogism either. Notice the phrase does not say "understanding seeking understanding." Faith is not so much intellectual assent to a set of propositions but a way of life. Try living as if the claims of the religion were true and see where that gets you. It could be nowhere or it could be to understanding. I myself haven't yet made such a leap, but the temptation is there.