This is the third unit, the book of the genealogy of Adam. The New Testament begins with the book of the genealogy of Jesus Christ (Matthew 1:1), the second Adam (I Corinthians 15:45). The phrase book probably indicates the source of written information obtained by Moses.
We have in Chapter 5 a sequence of the descent from Adam straight to Noah, giving us details of names and ages, and just adding comments about Adam, Enoch and Lamech. Adding up the ages, from Adam to the year of the flood, we find 1,656 years. This detail is given quite clearly in this passage.
The population, however, increased very much because Adam, like the rest of those mentioned, had sons and daughters, and all these also multiplied. The son of each one mentioned here is not necessarily his eldest son, since it is not said that sons and daughters came later, but that besides this child, he had more sons and daughters. Assuming that each couple had an average of 10 sons and daughters (probably many more, given their long age) at the time of Noah we arrive at a population of at least 20 million people of the last generation, another 5 million survivors of previous generations, a total of more than 25 million people!
In the first verse, the words “on the day”, have the meaning of when. That man was made by God in His likeness is again repeated: this was an act of special creation, after all the other things. Men and women are a unique creation (since the woman is part of man), and both together were called Adam when they were created: Adam comes from a root which means red earth: a way of reminding us where we came from - and where our bodies go! It was God who gave us that name - who knows if He had left it to Adam he would have taken to himself a more grandiose name!
This first couple had a son in their likeness (we know there were others before) whom they called Seth, the chosen, the indicated, prophetically knowing that from him would proceed the strain chosen by God. They also had other sons and daughters, which are not included in this narrative.
Five centuries after the birth of Seth his descendant Enoch was born: a prominent figure not only because he walked with God, had a relatively short life on earth for those times (365 years), did not die because God took him, but also because he prophesied about the second coming of Christ to take up his millennial kingdom (Jude 14-15). The same Hebrew words for “God took to himself” are used with respect to the transfer of Elijah (2 Kings 2:3, 5) meaning he did not die (Hebrews 11:5), because he pleased God by faith.
His grandson Lamech is also remembered for his prophecy when naming his son Noah: Noah through his obedience to God saved his family from the flood, and so preserved humanity from total destruction, and his lineage comes through to Christ, Saviour of all who fear God and believe in Him.
The narrative stops at the point where Noah was five hundred years old: this was when he was told by God to build an ark: a hundred years later (Genesis 7:6) the Flood came.
In its final part, we have a sad portrait of the moral and spiritual condition of mankind at that time. The sanctity of marriage was troubled by the lust of men, attracted only by the physical beauty of women.
The children of God - those who have invoked the name of the Lord (Genesis 4:26) – took for themselves the women they considered most desirable, "daughters of men" to satisfy their lust. They may also have been ambitious, despotic and autocratic rulers seizing both women and power in an attempt to gain all the authority and notoriety they could from those within their reach. Their progeny were, not surprisingly, adversely affected. Men were physically strong - there were giants among them. Of marriages between the children of God and the daughters of men appeared valiant men (the military) and men of renown (influential and powerful), where we see social castes and exploitation of the weak by the strong.
God was grieved over the increased wickedness on planet Earth. Every inclination of the hearts and thoughts of humanity was evil. So much wickedness has multiplied between mankind that the LORD repented: it does not mean that he changed his plans, because they are eternal, immutable, but the meaning is that, from a human standpoint, He was going to exterminate, sadly, that civilization which could not be repaired. Mankind had proved that, with only its own conscience to accuse it, it irreparably headed towards evil. Even those who feared God were being corrupted.
God then warned that His patience was exhausted; mankind would only have another 120 years of existence before the flood was released upon planet Earth in judgment of its perversion of authority, the state, justice and human sexuality.
Along with humanity, all land animals, birds and reptiles would be destroyed, except for specimens of each kind for fresh multiplication afterwards.
But there was a man whom God favoured: Noah and his is the narrative that follows.
1 This is the book of the genealogy of Adam. In the day that God created man, He made him in the likeness of God.
2 He created them male and female, and blessed them and called them Mankind in the day they were created.
3 And Adam lived one hundred and thirty years, and begot a son in his own likeness, after his image, and named him Seth.
4 After he begot Seth, the days of Adam were eight hundred years; and he had sons and daughters.
5 So all the days that Adam lived were nine hundred and thirty years; and he died.
6 Seth lived one hundred and five years, and begot Enosh.
7 After he begot Enosh, Seth lived eight hundred and seven years, and had sons and daughters.
8 So all the days of Seth were nine hundred and twelve years; and he died.
9 Enosh lived ninety years, and begot Cainan.
10 After he begot Cainan, Enosh lived eight hundred and fifteen years, and had sons and daughters.
11 So all the days of Enosh were nine hundred and five years; and he died.
12 Cainan lived seventy years, and begot Mahalalel.
13 After he begot Mahalalel, Cainan lived eight hundred and forty years, and had sons and daughters.
14 So all the days of Cainan were nine hundred and ten years; and he died.
15 Mahalalel lived sixty-five years, and begot Jared.
16 After he begot Jared, Mahalalel lived eight hundred and thirty years, and had sons and daughters.
17 So all the days of Mahalalel were eight hundred and ninety-five years; and he died.
18 Jared lived one hundred and sixty-two years, and begot Enoch.
19 After he begot Enoch, Jared lived eight hundred years, and had sons and daughters.
20 So all the days of Jared were nine hundred and sixty-two years; and he died.
21 Enoch lived sixty-five years, and begot Methuselah.
22 After he begot Methuselah, Enoch walked with God three hundred years, and had sons and daughters.
23 So all the days of Enoch were three hundred and sixty-five years.
24 And Enoch walked with God; and he was not, for God took him.
25 Methuselah lived one hundred and eighty-seven years, and begot Lamech.
26 After he begot Lamech, Methuselah lived seven hundred and eighty-two years, and had sons and daughters.
27 So all the days of Methuselah were nine hundred and sixty-nine years; and he died.
28 Lamech lived one hundred and eighty-two years, and had a son.
29 And he called his name Noah, saying, "This one will comfort us concerning our work and the toil of our hands, because of the ground which the LORD has cursed."
30 After he begot Noah, Lamech lived five hundred and ninety-five years, and had sons and daughters.
31 So all the days of Lamech were seven hundred and seventy-seven years; and he died.
32 And Noah was five hundred years old, and Noah begot Shem, Ham, and Japheth.
1 Now it came to pass, when men began to multiply on the face of the earth, and daughters were born to them,
2 that the sons of God saw the daughters of men, that they were beautiful; and they took wives for themselves of all whom they chose.
3 And the LORD said, "My Spirit shall not strive with man forever, for he is indeed flesh; yet his days shall be one hundred and twenty years."
4 There were giants on the earth in those days, and also afterward, when the sons of God came in to the daughters of men and they bore children to them. Those were the mighty men who were of old, men of renown.
5 Then the LORD saw that the wickedness of man was great in the earth, and that every intent of the thoughts of his heart was only evil continually.
6 And the LORD was sorry that He had made man on the earth, and He was grieved in His heart.
7 So the LORD said, "I will destroy man whom I have created from the face of the earth, both man and beast, creeping thing and birds of the air, for I am sorry that I have made them."
8 But Noah found grace in the eyes of the LORD.
Genesis chapter 5 verse one to chapter 6 verse 8.