Genesis 6 gives the sad account of the state of humanity prior to the worldwide flood during the days of Noah. Genesis 6:5 states, “The LORD saw how great the wickedness of the human race had become on the earth, and that every inclination of the thoughts of the human heart was only evil all the time.” The level of sin and corruption among the human population was staggering: people thought about doing evil “all the time.” For the strong and healthy individual, an evil lifestyle would have ramifications evidenced by disease and death. But the weak or unhealthy (babies, children, women, and the disabled) would have been immediately put in harm’s way by the evil actions of others.
In addition, “The sons of God saw that the daughters of humans were beautiful, and they married any of them they chose” (Genesis 6:2). In the Hebrew language, these “sons of God” were “bene elohim.” This term is usually applied to angels (see Job 1:6). Genesis seems to be stating that, somehow, there was a physical union between angels and human women. The unnatural offspring of this union were the “Nephilim” (Genesis 6:4). The word Nephilim is directly transliterated from the Hebrew. The ancient root of the word implies a “fall.” Whatever the word actually means (in some versions of the Bible it is translated as “giants”), Scripture describes the Nephilim as “the heroes of old, men of renown.” Some theologians believe that God could simply not allow this corrupt offspring to exist on the earth, and that was part of the reason for the flood.
What can be understood without question is that the world that was then, the world of Noah, was incredibly corrupt and perverted. Genesis 6:6 tells us that “The LORD regretted that he had made human beings on the earth, and his heart was deeply troubled.” The Lord’s “regret” is unlike ours. Creating mankind in the image of God was not a “mistake” on the part of the Lord. The Hebrew word nahem can also be translated “grieved.” The depraved actions of mankind grieved God in His most holy heart.
God responded to man’s sin in a holy and righteous manner, but also in a way that salvaged mankind. “So the LORD said, ‘I will wipe from the face of the earth the human race I have created—and with them the animals, the birds and the creatures that move along the ground—for I regret that I have made them.’ But Noah found favor in the eyes of the LORD” (Genesis 6:7, 8). Yes, all people on earth died except the eight people who were found righteous in the eyes of God: Noah, Noah’s wife, and Noah’s three sons and their wives. Scripture indicates that Noah testified to the world about the coming flood for 120 years. The people who perished in the flood died because they refused to acknowledge God or seek His forgiveness. Noah, on the other hand, is described as righteous, blameless, and obedient in that he “walked with God” (Genesis 6:9).
Noah and his family became our ancestors. None of us descend from the Nephilim or the unrighteous line of Cain (since Noah descended from Seth). The polluted, unrighteous population of the world of Noah disappeared from the earth. Mankind was salvaged, and from the line of righteous Noah came the Son of Man, Jesus Christ our Lord, who died to save those who call upon His name.
 Got Questions Ministries. (2010). Got Questions? Bible Questions Answered. Bellingham, WA: Logos Bible Software.