What does Genesis 6:5 mean?

This heartbreaking verse echoes Genesis 1:31. That verse described God seeing all that He had made after the sixth and final day of creation and observing that "behold, it was very good." Now, hundreds of years after human sin had entered the world, God sees that man's wickedness is the thing that is great in the earth. In addition, God sees that every intention of the thoughts of the human heart is only evil continually.

Taking the genealogies of the past chapter literally, this is especially sad. The long lifespans of Genesis 5 imply that there was an almost-unbroken line of eyewitnesses to man's earliest history, right up to the year of the flood. Mankind's sin is not the result of error or drifting or ignorance. It's the result of a deliberate rejection of God.

God's conclusion about the state of humanity is an all-encompassing declaration of human depravity. Left to follow our own way, apart from God, men and women will always choose evil. It's not just what we do; it's who we are without His direct involvement and transformation of our hearts. This goes a long way to explaining God's apparent decision to drastically reduce human lifespans (Genesis 6:3).

This verse offers another clue to the nature of humanity: Our sinfulness, our inclination to do what is harmful, begins in our minds or hearts. In our Godless state, we do not happen into sin. We intentionally plan for it. It's where we want to go. It's not just our actions that are the problem; it is the hearts and minds that produce those actions.

We haven't improved over the centuries. Our natures remain the same. When describing the Day of the Lord in Matthew 24, God's coming judgment for human sin, Jesus declares that it will be as in the days of Noah (Matthew 24:36–39). All these years later, without God's redemption and recreation, the human heart remains inclined to plan for evil continually.