PRINCIPLES FOR READING THE OLD TESTAMENT AND ITS NARRATIVES
1) The OT is not the NT. It does not involve tales about Christians. One should not expect OT people to behave, or even to believe, exactly as Christians should and do. This means that one has to look at figures in the OT in a more general way. They can be examples of trusting God, like Abraham, or courage, like Elijah, or vision like Isaiah, but they cannot be examples of born again Christians. This means that we should not expect even the best of them to always behave the way we expect Christians to do— avoiding adultery, killing etc. Even some of the OT ‘heroes’ and ‘heroines’ commit enormous sins— e.g. King David. But they should be judged on the basis of the covenant which they are under— in this case the Mosaic covenant. Even by those lesser standards, there are no perfect saints to admire in the OT.
3) Only those portions of the commandments from the OT that are reaffirmed in the NT are still binding on Christians— e.g. loving God with one’s whole heart and neighbor as self.
4) Even so one can always find a good applicable lesson from any OT text that can be applied to the Christian life, if one asks the right questions of the text— e.g. What does this tell us about God, what does it tell us about God’s people or humankind in general, what does it tell us about God’s relationship with his people? And when the ethical principles carry over into the NT we can still ask of an OT text—What would God have us do on the basis of this or that text (e.g. worship God and serve only God as God; have no idols; do not steal etc.).
Deriving lessons or applications from OT texts is tricky, especially from OT narratives. We have to keep asking the question— Why is this story told, and what if anything is it trying to teach us (besides just plain history)? Sometimes Christians have made the mistake of assuming that if we find a narrative in the Bible that therefore that gives us carte blanche to imitate this or that person’s behavior in the narrative. Not necessarily. Some stories are go and do otherwise kinds of story (e.g. David and Bathsheba) and some stories are go and do likewise (e.g. the story of Jonah’s obedience to God in going and preaching to Nineveh). Basically, a simple rule of thumb is look for positive or negative repeated patterns in the narratives. Positive repeated patterns suggest the writer wants us to go and do likewise, and vice versa with negative repeated patterns. But you can’t simply read a narrative and use it as a justification for your own behavior because ‘that story is in the Bible’. Well yes, the story of Judas betraying Jesus is not the Bible but that doesn’t mean you should emulate his behavior. And one needs to exercise even more caution when handling OT stories which do not involve Christians or Christian principles (e.g. the whole prayer of Jabez debacle).
If you want a lot more along these lines of how to read the Bible see my Reading and Understanding the Bible, (Oxford U. Press, 2014)