Couple of considerations:
- Jesus referred to the flood in the context of judgment. If we hold that the flood was myth or fable, then we imply Jesus was lying or was misinformed--neither trait one we associate with lord and savior
- God's promise to Noah was that He would never again flood the earth the way He did. However, there HAVE been local floods since that time. So, if the flood of Noah was merely a local flood, then God was lying.
- I'm not trying to impute motives on your part, but I will say that often people dislike, or try to disprove the idea of the Noahic flood, because they are uncomfortable with the idea of divine judgment.
No, it wasn't God who wrote Genesis, some say it was Moses putting to paper what had long been an oral tradition in pakistani/hebrew culture. A true story of survival at sea during a hurricane was turned into a myth/fish story that gets bigger with each telling. It's really no different than other myths : greek gods, aryan superiority, the list goes on and on; even today we have the myth of OBL living in a cave, sending out his assassins, a medieval arabic myth. Don't underestimate the POWER of myth, it is MYTHS that underpin religions. It was a MYTH that impelled the 9/11 hijackers to kill so many.....As to Jesus and floods : his main clue : "and the lightning flashed from the east even unto the west". Put that(counter EMF force) together with the GREAT earthquake and HUGE hailstones...and you've got what I figured out in 1979.