The gullibility in your statement is what is staggering. Have you ever read any C.S. Lewis? He could show you how to distinguish between history and fiction. I guess 3000 year track record of its having been taken as true history isn't evidence in these parts, huh?
CS Lewis was indeed able to distinguish history and fiction; and being an expert in literature he certainly did not make the facile mistake of treating Genesis as a history. Lewis regarded it as myth, and he regarded that as a compliment, not a denegration.
Lewis was not much concerned with whether events took place in history exactly as recorded in Genesis; in his view this makes little difference to the importance of the account or why it was recorded. There is a good discussion of how Lewis treated the bible at
The Unfundamental C. S. Lewis: Key Components of Lewis's View of Scripture by Duncan Sprague. Sprague is a creationist himself, but he is a fan of Lewis. He does, however, critize Lewis for failing to declare Genesis as historical. On this, Lewis is plainly the more expert in literature and the more sensible in recognizing that historicity is not the point or the focus.
Lewis regarded the bible as showing a progression from myth to history. Thus early Genesis he regarded as "folktale" and the flood as "legendary", but Jesus as fully historical. Quoting
C. S. Lewis's Theology by James Townsend:
In his books Lewis amplified on his understanding of the Bible’s inspiration: "The earliest stratum of the Old Testament contains many truths in a form which I take to be legendary, or even mythical . things like Noah’s Ark or the sun standing still upon Ajalon," while in the New Testament "history reigns supreme." Elsewhere he wrote, "The first chapters of Genesis, no doubt, give the story in the form of a folktale . " Referring to the notion that "every sentence of the Old Testament has historical or scientific truth," Lewis admitted: "This I do not hold, any more than St. Jerome did when he said that Moses described Creation ”after the manner of a popular poet’ (as we should say, mythically) or than Calvin did when he doubted whether the story of Job were history or fiction." Again, Lewis penned: "The Old Testament contains fabulous elements" which would include "Jonah and the Whale, Noah and his Ark, . but the Court history of King David is probably as reliable [historically] as the Court history of Louis XIV."
Note that Lewis also disagrees with the notion that Genesis has always been read simply as history in the past. Ancient scholars also could recognize the use of myth and poetry and other literary forms. In short, Lewis is no support for your perspective at all.
Cheers -- Sylas