re: “ What is not believable is that God would have wiped the entire planet over sin, only to have sin back in business 50 years later as if nothing had happened; I give God credit for being a bit brighter than that and assume that part of the story was added by priests at a later date.”
I think you may be presumptuous to assume that God judging the world to the point of wiping out humanity (except for Noah and his family) because of its sin as “unbelievable”, and not so bright of God because sin “is back in full business 50 years later”.
First off, God judged people’s sin several times, not to the point of world-wide destruction perhaps, but He did destroy nations who, after hundreds of years of warning of judgement, refused to stop what they were doing.
Two, we are not given all the information in Genesis as to what possible warnings were exteneded to mankind prior to the flood, but given the pattern God usually demonstrates in the Old Testament, there were probably several warnings and centuries of waiting before ultimate judgement came.
Three, since we as human beings do not have all the foreknowledge and omniscience that God has, it is very foolish of us to judge God’s actions as to whether or not it was “bright of Him”. After all, God’s loving us to the point of coming as a human being and dying on the cross to pay for the guilt of our sins (that we committed against Him) - was that “smart” of God? After all, sin still continues unabated, right?
Fourth, God, as Creator of the universe and all life, it is His prerogative to do whatever He wants with it.
Again, I’m not fishing for an argument, just offering another point of view.
There is evidence of massive floods in the past, Noah’s was probably just one of them.