There are a lot of Bible passages non-believers point to and say, "See, that makes no sense." But there is one I haven't seen discussed, in which a Bible author stepped into a pothole in an ill-conceived attempt to force his story to make sense.
People aware of the history of the Bible understand that it didn't always exist in its present-day format. The Torah (the first five books of the Old Testament, starting with Genesis) was originally an oral tradition, maintained by storytellers who fascinated the early Jews with tales of the origins of their people. Parts of it were written down as early as the 8th century BCE, but it didn't take its current form (more or less) until a couple of centuries later, and wasn't regarded as Holy Canon until around a century after that.
As a result of its oral foundations, there are numerous places in the text in which mutually inconsistent versions of the same story have been jammed together to make a single narrative. That phenomenon begins as early as possible, with two different versions of the Creation myth, in the first two chapters of Genesis, which disagree on the order in which various creative events occured, a discrepancy that recent translations have tried (unconvincingly) to fix by inserting awkward changes in verb tenses. Further on in Genesis, during the multi-generation saga of Abraham's family, there is a story that is told three different times, in which an important Bible patriarch, during his travels, tells everyone he meets that his wife is instead his sister, so that any man who desires to take her won't have to kill the patriarch first, and the patriarch is eventually confronted over the lie. The three versions of the story disagree on basic details, such as which patriarch it was and who confronted him, with some characters common to the first two versions, some common to the latter two, but no character appearing in all three. Believers insist that the presence of the three versions of the story must mean all three happened, as opposed to the more obvious explanation that such confusion is to be expected when stories are passed along orally.
Anyway, my actual subject here will be the story of Noah and the Ark. Within it, there is a little-noticed instance of a portion of the narrative being told in two incompatible versions. It is rare that anyone, among people who claim to have read the Bible (surely greater than the number who actually have) seems aware that the second version is even there, and I haven't read about anyone having discussed its implications.
The account of the Flood starts in the middle of Genesis 6, when God sees that the world has become "corrupted," and decides to erase the human race and start over. Curiously, God also condemns the world's animals for no stated reason, and decides to send a great flood to wipe away the corruption, along with the blameless animals. It is easy to wonder why God, in that case, wouldn't simply get rid of all living things, without exception, and repeat the Creation process, but the narrative explains that "Noah was a righteous man" to justify God giving him a pass, without accounting for the later story that starts with Noah getting so drunk he passes out naked in his tent. In any case, God does decide to save that one righteous man (and his wife, his three sons and their wives, whose degree of righteousness is not specified), and gives Noah and family the task of saving enough animals so as to repopulate the Earth.
Here is where the narrative gets murky. In Genesis 6:19-20, God tells Noah, after instructing him in the specifications for the Ark, "You are to bring into the Ark two of all living creatures, male and female, to keep them alive with you. Two of every kind of bird, of every kind of animal and every kind of creature that moves along the ground will come to you to be kept alive." That couldn't possibly be worded more clearly.
Then just two sentences later (Genesis 7:2-3), in a passage no one ever seems to remember is there, God contradicts all that: "Take with you seven pairs of every kind of clean animal, a male and its mate, and one pair of every kind of unclean animal, a male and its mate, and also seven pairs of every kind of bird, male and female, to keep their kinds alive throughout the Earth."
There is more here than simple contradiction. There are obviously two different storytellers involved, and it's clear what the second one was worried about: the unclean animals. Judaism had maintained a traditional belief, incorporated into its dietary laws, that certain animals are "unclean." The most famous such animal is the pig, though other examples include camels and the rock badger, less well-known because the issue of whether to eat them or not rarely arises in the modern day.
So in the Biblical text, the second version of the Noah tale is told by a storyteller who must have asked himself the question: In rescuing the animals, why did God want to save the unclean ones? If God is so incensed by the corruption of humans that he wants to kill them all, why not take advantage of his own plan and get rid of the unclean animal species as well at the same time? Why would he save any pigs?
So the storyteller decided an adjustment was required. Yet it couldn't be as straightforward as God simply telling Noah not to save the pigs, because that would make it impossible to explain why, after the Flood, pigs still existed.
So the storyteller arrived at the new strategy: Have Noah save a lot of each good animal species, but only a minimal number of bad ones. In pursuit of that strategy, the storyteller boosted the number of pairs of each clean animal to seven, while specifying that only one pair of each unclean animal should be saved.
Yet that makes far less sense than the earlier "two of each, no matter what they are" version of the story: Suddenly it is acknowledged that God hadn't forgotten that there were unclean species, yet for no imaginable reason, he still wants to save them.
No reason? Maybe an ecological one? We know, in the twenty-first century, that deleting an entire species of any living thing can play havoc with the the rest of the biosphere: other species have come to depend on the existence of that missing one. Presumably God, who "created" the ecology to begin with, would know the rules. Yet that still makes no sense: God, if he exists and created it all, not only knows the rules, he made the rules. It's impossible that he would be bound by them -- he can change them at will. And further, if an unclean species needs to remain because some other animal needs to eat it, then that animal would be unclean: how could a clean animal eat an unclean one and still be clean? So the uncleanness spreads throughout the food chain. Surely God should never have made the unclean animals in the first place, but he did -- and now for some reason, despite his omnipotence he's unable to get rid of them?
And there is a second serious problem with version 2 of the specifications of how many animals of each type to save (no, I'm not the first person to notice this): in the Bible narrative, God's mention of "unclean" animals in the Noah story comes many generations before God explains which ones they are. In the history recorded in the Bible, no animal is ever denounced as "unclean" by God until the time of Moses, who was way down the historical road from Noah. Noah shouldn't have known what God was talking about. If God did, at some point, explain to Noah which animals were "unclean," without that conversation being mentioned in the narrative, then that would be knowledge possessed by all of humanity: only eight people survived the Flood, and they all helped load the Ark and would have all had to know which animals were the "unclean" ones, since that would determine how many of them went onto the Ark. So why, if every human after Noah knew which animals were unclean, would God have to explain it all over again later in Moses' time as if nobody had known until then?
The obvious explanation, in the real world, is that the storyteller was so concerned about preempting the question of why God saved the unclean animals (since their later existence implied that he must have) that he posited that God had indeed saved them, for no known reason, but had taken into account their undesirability by putting them at a seven-to-one disadvantage on the Ark. And the storyteller, familiar with the tradition of certain animals being unclean, either forgot, overlooked, or didn't realize that mentioning them as an issue in Noah's time came many generations too early in the narrative. It's an anachronism similar to Shakespeare famously not realizing that mechanical clocks didn't exist in the time of Julius Caesar.
It's all a pretty big black mark against the believability of the Bible, because the problem goes beyond the question of whether the Bible is accurate history. Many believers acknowledge that many, if not most, Bible stories are "metaphorical": that the stories are meant to "teach us something," rather than being exact historical accounts. Yet those same people still maintain that the Bible is the Word of God: that when it tries to "teach," it is God who is doing the teaching. But the entire idea of God being the author of the Bible, speaking to us through the scribes who wrote it down, is brought into question by the contradictions, the inconsistencies of narrative, and in this case, by a storyteller who, ironically, poked holes in the story he was telling exactly because he was trying to fix it. That isn't something an omniscient god would do.