If you discount the story of Jonah, what other parts of the bible are you going to throw out as untrue? If you throw out one part, you may as well throw it all out...
Not so. Not so at all. Many Biblical scholars believe that the Biblical account of creation was written allegorically, as are other parts of the Bible (like the previously mentioned story of Jonah). None of that detracts from the heart of the matter though...the mission and ministry of Jesus.
