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James Kraft
One of the reasons I believe for the flood and saving Noah and his family, are because Noah was still pure from Adam. The angels who left their first estate, the fallen angels came and had sex with the daughters of men hoping to destroy the human race so that the Messiah could not be born into the human race. God saved Noah to keep man from being corrupted by the inhuman race.
We know it happened again after Noah, as I believe Goliath was the offspring of fallen angels. Some of the bones of these hybrids have been found to be 30 feet tall.