In what is already a very old commentary I read that the fourth Gospel is regarded by one school as a 'spiritual romance', 'a poem not a history', to be judged by the same canons as Nathan's parable, the book of Jonah, Paradise Lost 'or, more exactly, Pilgrim's Progress'. After a man has said that, why need one attend to anything else he says about any book in the world? Note that he regards Pilgrim's Progress, a story which professes to be a dream and flaunts its allegorical nature by every single proper name it uses, as the closest parallel. Note that the whole epic panoply of Milton goes for nothing. But even if we leave our the grosser absurdities and keep to Jonah, the insensitiveness is crass - Jonah, a tale with as few even pretended historical attachments as Job, grotesque in incident and surely not without a distinct, though of course edifying, vein of typically Jewish humour. Then turn to John. Read the dialogues: that with the Samaritan woman at the well, or that which follows the healing of the man born blind. Look at its pictures: Jesus (if I may use the word) doodling with his finger in the dust; the unforgettable nv vuz (13:30). I have been reading poems, romances, vision-literature, legends, myths all my life. I know what they are like. I know that not one of them is like this. Of this text there are only two possible views. Either this is reportage - though it may no doubt contain errors - pretty close up to the facts; nearly as close as Boswell. Or else, some unknown writer in the second century, without known predecessors, or successors, suddenly anticipated the whole technique of modern, novelistic, realistic narrative. If it is untrue, it must be narrative of that kind. The reader who doesn't see this has simply not learned to read. I would recommend him to read Auerbach.
John Beversluis is critical of this claim. He says:
But that is not an argument. It is a question based on the false assumption that wide reading in a particular genre necessarily makes one's judgment more reliable than narrow intensive reading in the same genre.
Well, if you put a necessity operator in, I suppose it is a false assumption. It could be that someone who engaged in a wide reading of a genre could have worse judgment than someone who read more narrowly and intensively. Still, one could certainly make mistakes reading narrowly within a particular genre and ignoring the types of literature extant at the time. For example, calling the Gospels novels is a mistake someone might make who is familiar with Biblical literature but is not aware that no one wrote novels in ancient times. It certainly seems reasonable that Lewis could have knowledge, as a literary scholar, that would allow him to avoid mistakes that a narrowly focused biblical scholar could make.
This is a particularly forceful consideration when one realizes that the idea that John is a spiritual romance is not a consensus claim amongst biblical scholars. There are plenty of scholars who think that John is a good-faith attempt to record what Jesus really said and did.
But also notice that Lewis doesn't just appeal to his own authority as a biblical scholar, he cites an authority, the Jewish scholar Auerbach, whose Mimesis made him a heavyweight in literary criticism.
Gene Veith, in his treatment of Auerbach's argument says:
Homer, Auerbach shows, puts everything in the foreground — giving us what the characters look like, describing their surroundings in detail, and even telling us what they are thinking. This approach, which has become the model for Western fiction, is “to represent phenomena in a fully externalized form, visible and palpable in all their parts, and completely fixed in their spatial and temporal relations,” says Auerbach.
He contrasts this highly-imaginative approach to the way the Bible in Genesis describes the sacrifice of Isaac. We do not know what Abraham or Isaac look like; there is no description of the landscape; we are not told what Abraham thinks as he prepares to sacrifice his son; nor are we informed why God acts as He does. Such meaning is in the “background,” requiring interpretation and reflection and opening up untold depths.
This kind of narrative testifies to the real because it is messy, unpredictable, and compels, just like real life. Auerbach says that the story of David has to be historical. “In Absalom’s rebellion, for example, or in the scenes from David’s last days, the contradictions and crossing of motives both in individuals and in the general action have become so concrete that it is impossible to doubt the historicity of the information conveyed.”