On interpreting metaphors and genres
Scholar Ben Witherington has a nice post that covers a few common mistakes I often see people make when interpreting the bible.
One thing that surprises me time and again is how bad people are at understanding the concept of, and interpreting, metaphorical language. Now I'm sure most people have done poetry at school, and that if you shoved a line of poetry under their noses and said "identify the similes and metaphors" they could do a reasonable job. And if you asked them to "explain the poet's meaning here" they could probably give a reasonable explanation about what the meaning behind the metaphorical language was and what the poet was saying.
Yet this knowledge seems to fly out the nearest window when it comes to the Bible. Put a line from the bible in front of someone and say "identify the metaphorical language" and you'll be met with blank stares. If you suggest that there's metaphorical language present then your words will be understood as meaning that you are denying the literal meaning of the text (ie refusing to believe the bible) and that this is because you don't believe in the supernatural and that you justify this by 'spiritualising' the text (eg they think you're talking about making the resurrection of Jesus a 'metaphor' for the 'new life' that people feel like they receive when they hear his marvelous teachings). The concept of trying to correctly identify instances of metaphorical language in an attempt to understand authorial intent just doesn't seem able to be fathomed by a surprisingly large number of people, no matter how much effort is put into explaining it.
I think this ties into another problem Witherington isolates - genre identification. Too many people treat the entire bible as if in genre it was a Systematic Theology textbook. ie any and all sentences are intended with dry literalism to state theological facts and the target audience is any theologically-interested reader. Systematic Theological language tends to be always literal and never metaphorical, hence (I suspect) the difficulty some people have with the very concept of metaphors in the bible. This problem also results in a failure to pay attention to the genre of the biblical passage being interpreted. One of the most glaring genre errors I see regularly is people interpreting passages as meaning that "no one can ever do good, so don't bother trying" in sections where the genre is Moral Exhortation.