6:1 multiply. God had commanded Adam and Eve to “multiply” (Genesis 1:28). With each man and woman enjoying hundreds of years of parental productivity plus almost ideal environmental and climatological conditions, the earth could well have been “filled” with people long before the Flood. For example, an initial population of two people, increasing at the rate of 2% annually (estimated to be the annual growth rate at present) would generate a population of well over ten trillion people in 1656 years (the time span from Adam to the flood).
6:2 sons of God. The identity of these “sons of God” has been a matter of much discussion, but the obvious meaning is that they were angelic beings. This was the uniform interpretation of the ancient Jews, who translated the phrase as “angels of God” in their Septuagint translation of the Old Testament. The apocryphal books of Enoch elaborate this interpretation, which is also strongly implied by the New Testament passages (Jude 6, II Peter 2:4-6; I Peter 3:19,20). The Hebrew phrase is bene elohim, which occurs elsewhere only in Job 1:6; 2:1; 38:7. In these three explicitly parallel usages, the contextual meaning can be nothing except that of angels. A similar phrase bar elohim, occurs in Daniel 3:25, and another, bar elim, occurs in Psalm 29:1 and Psalm 89:6. All of these also refer explicitly to angels. The intent of the writer of Genesis 6 (probably Noah) was clearly that of introducing a monstrous irruption of demonic forces on the earth, leading to universal corruption and eventual judgment.
6:2 took them wives. The “taking” of these women most likely refers to fallen angels, or demons, “possessing” their bodies. The word “wives” (Hebrew ishshah) is better translated “women.” There is no necessary intimation of actual marriage involved. By this time in history, anarchism and amorality were so widespread that these demons were easily able to take possession of the bodies of multitudes of ungodly men; these in turn engaged in promiscuous sex with demon-possessed women, with a resulting rapid population growth, Satan perhaps hoping thereby to generate a vast army of human recruits to his rebellion and also to thwart the coming of God’s promised Seed by thus corrupting all flesh.
6:3 My spirit. One of the ministries of God’s Holy Spirit has always been to convict man’s spirit of “sin, and of righteousness, and of judgment” (John 16:8). Man is also “flesh,” however, and there is perpetual conflict between the flesh and the spirit, even in the life of a believer (Romans 8:5; Galatians 5:16,17). God is long-suffering with respect to man’s rebellion, but only for a time: the hour of His judgment must eventually arrive.
6:3 hundred and twenty years. This prophecy was apparently given, perhaps through Methuselah, just 120 years before the coming Flood. The prophet Enoch had already been translated. Shem, Ham and Japheth had not yet been born and God’s specific commands to Noah (Genesis 5:32; 6:10,13,21) not yet given.