I agree with the general point expressed here about the difficulty of interpreting the Bible , but it's worth dwelling on because recognizing the existence of--let alone being able to identify or produce--different interpretations of a text is one of those sophisticating reading skills that even well-educated adults have a hard time mastering. One has to recognize the parts of the text that are "in play," which, as the example attests, includes the silences in the text, and then imagine the background assumptions and rhetorical techniques that are required to be able to produce an alternate reading. Then one actually has to produce an alternate reading. It's no surprise that many people go completely from one interpretation to another with little or no way-station in between.
When I was teaching, I used to exploit this for pedagogical ends. At Chicago, we would start out the year by reading the Republic, which is notable for the wide variety of ways people have understood it and which has some famously ambiguous passages. First assignments are tricky, because one wants to set the proper tone: this class will be neither easy nor impossible, but will require work. The last is especially important for people who feel that writing thesis-essays is easy either because they were able to produce consistently in high school, or they don't take non-scientific forms of study seriously. Thus, the assignment: take one of the famous (pre-selected) passages of the early books and give two interpretations of it. No need for introductions, thesis statements, or anything else: just two interpretations. The success rate was usually around 25%. This would lead to office hours where the other 75% of students would come to ask what was wrong. I'd ask them to put aside their papers and just explain to me the difference between their two interpretations, and most of those explanations would end with the student realizing they had just written the same interpretation twice. Somewhat chastened, they were ready to work more seriously.
That's the reality, I think: it's difficult enough to pass along one complete interpretation in all its nuances--and a liberal Protestant reading of the Bible is about nothing if not an endless series of nuances--for a book that is highlighted by changing narrative modes, genres, and rhetorical styles, all of which lays on top of the more fundamental question of how to read a book originally written for a different audience. I've come to think of the Bible as the easiest difficult book to read, or the most difficult easy book, for exactly this reason.