One of the fundamental myths of Judaism - and therefore of Christian and Muslim faiths - is the exodus story. Unlike other myths (e.g. Jesus), this one can (and was) tested: hundred of thousands of people are supposed to have spent 40 years in a desert which was never heavily populated since. It is inconceivable that not a shred of evidence has remained. Yet - not one was ever found, and not for lack of trying.
I may be naive to assume that facts can change beliefs, but still: wouldn't this single fact enough to crumble the foundations of Judaism and the related faihts?
I can't see how you argue the exodus story is "symbolic"