Many Christians assert this passage from Genesis is the point at which God ended the long years of man (many lived well in excess of 600 years) and limited humans to an age of 120 years.
There is, however, just one small problem with that assessment. Many, many men who lived after the flood lived longer than this prescribed amount of years.
Now, Noah and all of his sons lived far in excess of 120 years, but it could be easily argued that since those men were born before God’s declaration, it did not apply to them.
However, starting in Genesis 11:10…
Shem, son of Noah, begets Arphaxad.
Arphaxad lives 403 years.
Shelah lives 403 years.
Eber lives 430 years.
Peleg lives 209 years.
Reu lives 207 years.
Serug lives 200 years.
Nehor lives only 113 years, and is the only one of the bunch to live within the 120 year time frame.
But wait! There’s more!
Terah lives 205 years (he has his sons at 70!)
Abraham lives 175 years, and Sarah herself lived 127 years.
Gen 25:7 and 23:1
Issac lives 180 years.
Jacob lived 147 years.
Levi lived 137 years.
Kohath lived 133 years.
Amram lived 137 years.
All of these men lived longer than 120 years save one. We know God is not a liar. If God said “man can only live 120 years” then it would be so, and these men would not have lived a day past 120, yet all of them (save one) did, and some to a great extent.
So what then can we conclude? The facts show that the common interpretation of this passage is incorrect.
So if it is not referring to the age limit of man, what does it refer to?
In Gen 6:3, the word commonly translated as “mortal” can also mean “corrupt”. The passage is saying humans had become corrupted.
The depravity of man is a doctrine any Christian should be familiar with, and if you aren’t you can read this summary of the doctrine. When Man fell in the Garden of Eden by rebelling against God’s authority, he became corrupt. Much like a data file that becomes corrupt on a computer, there is no hope in the data recovering itself. By rebelling, Mankind had created a privation of righteousness, a lack of goodness within himself. We call this absence of God’s perfection sin or evil.
The Bible tells us in places like Romans 1 and Ephesians 4 that sin begets more sin. Sin is a downward spiral that is always getting worse, and never better. Without God’s intervention, mankind sunk deeper and deeper into depravity with no hope of escape.
Therefore, Genesis 6:3 can be seen as a judgement on Man. He is corrupt. He will never change. He must be destroyed.
It is likely then, that the Lord was in fact declaring his plans for the Flood. The 120 years then, are the number of years mankind has left before this judgement is executed. Enough time for Noah to build the Ark.
Praise God, however, for he preserved Noah and his family, who walked with God. Through that one family we all are descended, and through that preserved bloodline came Christ our Lord and Savior.
In many ways, the Flood was a dress rehersal for the final Judgement on Man and Sin due on the Day of the Lord, when Christ returns. We know this from passages like those found in 1 Peter and 2 Peter.
So why did the ages of humans drop so sharply after the Flood? The explanation is genetics. Adam and Eve were created perfect and flawless, but after the Fall, sin and death pervaded all Creation, infecting it with entropy, or decay. This decay affected human genes, which began to show abnormalities. These imperfections eventually killed off humans, though since they were very well made, it took many centuries. As humankind multiplied and time rolled on, however, the ages of humans start to drop slowly. The human genome is losing its perfection, and the new humans being born are weaker and weaker, and thus dying sooner.
After the Flood, Noah’s descendants had no choice but to marry with their brothers and sisters to procreate. We all know that unions between close relatives is a bad idea because the offspring are likely to be defective. This is because abnormal genes are recessive. You have to get a matching pair of bad genes to actually have a defect occur. When the baby is born of two close relatives, the chance for a matching pair is very high because their genetic code is very similar. When Noah’s descendants married, they all but guaranteed a proliferation of genetic defects in their children, cutting their lifespans in half almost at once. Of course, this still meant they lived some 200 years, but to those who can remember their relatives living far in excess of that, I’m sure it was a tragedy and a reminder of the price of sin.
So what are we to take away from Genesis 6:3? One, that humans are totally corrupt with sin from the Fall. Two, that God will ultimately deal with that sin in Judgement. Three, that God in His mercy has delayed His judgement for a fixed time period in order that some may be saved. Four, only those who submit to God’s redemptive plan will be saved. It was an Ark for Noah. For us, it is the person of Jesus Christ and His Gospel; that if you submit to Him as Lord and believe that God raised Him from the dead, you will be saved.