Walter Russell Mead uses Advent, the season of the liturgical calender when Christians "wait" for the coming of the Messiah at Christmas, to ponder how we read the Bible:

[These stories] validity doesn’t depend on whether there “really was” a prodigal son who returned to his father, or whether police reports in Jericho would corroborate the story about the Samaritan. The parable of the Good Samaritan doesn’t lose its force if archaeologists can’t find the receipt for the innkeeper’s bill.

Those examples of Jesus’ actual method of teaching—of God’s process of revelation—condition the way I and many other Christians down through the centuries have read the holy books. As far as I can make out, this is the tradition in which C.S. Lewis read the Bible. It is a serious but not always literal approach. It doesn’t run around with a crowbar gleefully smashing the credibility of biblical narratives, but it doesn’t assume that every book or passage of the Bible aspires to the same kind of literal Truth. The famous story of Jonah and the whale reads a lot more like a parable than like a newspaper article; for many Christians it’s enough to see that God teaches us in parables and stories in the Bible, just as Jesus did during his ministry.