This section’s details have been the subject of endless debates, often leaving the obvious untouched. It must be remembered that it is part of the ṯôleḏôṯ beginning in 5:1. Whatever view one takes of the details, it is clear that these verses show how wicked the human race had become, and that death was its ongoing punishment.
6:1-4. Many have suggested that the sons of God were the godly line of Seth and the daughters of men were the Cainites. But this does not do justice to the terminology or the context. Others view the “sons of God” as angels (as in Job 1:6), who cohabited with women on earth. This, however, conflicts with Matthew 22:30. The incident is one of hubris, the proud overstepping of bounds. Here it applies to “the sons of God,” a lusty, powerful lot striving for fame and fertility. They were probably powerful rulers who were controlled (indwelt) by fallen angels. It may be that fallen angels left their habitation and inhabited bodies of human despots and warriors, the mighty ones of the earth. It is known from Ezekiel 28:11-19 and Daniel 10:13 that great kings of the earth have “princes” ruling behind them—their power is demonic. It is no surprise that in Ugaritic literature (as well as other nations’ literature), kings are described as divine, half-divine, or demigods. Pagans revered these great leaders. Many mythological traditions describe them as being the offspring of the gods themselves. In fact bn’lm (“sons of the gods”) in Ugaritic is used of members of the pantheon as well as great kings of the earth. In the Ugaritic legend of the Dawn, the chief god of the pantheon, El, seduced two human women. This union of a god with human women produced Šḥr (“Dawn”) and Šlm (“Dusk”) who seem to have become goddesses representing Venus. Thus for the pagans, gods had their origin in copulation between gods and humans. Any superhuman individual in a myth or any mythological or actual giant would suggest a divine origin to the pagans. Genesis 6:1-4, then, describes how corrupt the world got when this violation was rampant. It is also a polemic against the pagan belief that giants (Nephilim; cf. Num. 13:32-33) and men of renown (Gen. 6:4) were of divine origin, and that immortality was achieved by immorality. The Canaanite cult (and most cults in the ancient Near East) included fertility rites involving sympathetic magic, based on the assumption that people are supernaturally affected through an object which represents them. Israel was warned to resist this because it was completely corrupt and erroneous. The passage, then, refutes pagan beliefs by declaring the truth. The sons of God were not divine; they were demon-controlled. Their marrying as many women as they wished (possibly this is the origin of harems) was to satisfy their baser instincts. They were just another low order of creatures, though powerful and demon-influenced. Children of these marriages, despite pagan ideas, were not god-kings. Though heroes and “men of renown,” they were flesh; and they died, in due course, like all members of the human race. When God judges the world—as He was about to—no giant, no deity, no human has any power against Him. God simply allots one’s days and brings his end.
6:5-8. God’s words concerning the human race are filled with pathos. People’s wickedness was great, and every inclination (better, “plan,” yēṣer) of their hearts was only evil continually (cf. 8:21, “every indication of his heart is evil from childhood”). God had made man by design (yāṣar, “to form by design”; 2:7), but man had taken that capacity given to him and produced evil alone. There is hardly a stronger statement in the Bible about the sin of mankind. This passage gives insight into Jesus’ explanation that “before the Flood people were eating and drinking, marrying and giving in marriage” (Matt. 24:38)—seemingly a harmless statement until its context is studied. In addition man was “corrupt” and “full of violence” (Gen. 6:11, 13). The wordplays in verses 5-8 are striking. God “repented” (kjv) that He had made man because the sin of the race filled Him with pain. The words “repented,” “pain,” and “made” go back to chapters 3 and 5. Lamech longed for comfort (nāḥam), from the painful toil under the curse (5:29). Now God “repented” (nāḥam, was grieved, niv) that He had made man because human sin pained Him (6:6). This is why pain was brought into the world—God was grieved with sin. But now God, rather than comforting man, “repented” after making him. This gave an ironic twist to Lamech’s words. God determined to destroy them all. (“Repented” does not suggest that God changed His mind, for He is changeless [Mal. 3:6]. Instead, it means that God was sorrowful.) Even though swift judgment would fall because God’s Spirit would not always shield (dûn; “shield” is better than niv‘s “contend with,” Gen. 6:3) mankind, the judgment would be delayed 120 years (v. 3). During this time Noah was “a preacher of righteousness” (2 Peter 2:5). Noah was a recipient of God’s grace and therefore was spared from the judgment (in contrast with those who aspired to immortality). In the time of Moses, Israel would know they were chosen of God and should walk in righteousness. They, as God’s people, would meet the Nephilim, the Anakites (Num. 13:33), and the Rephaites (Deut. 2:11; 3:13; Josh. 12:4) when they entered the land. But Israel should not fear them as demigods. God would judge the corrupt world for its idolatry and fornication. And in the latter day the wicked will suddenly be swept away by judgment when God will establish His theocratic kingdom of blessing (Matt. 24:36-39).
Walvoord, John F. ; Zuck, Roy B. ; Dallas Theological Seminary: The Bible Knowledge Commentary : An Exposition of the Scriptures. Wheaton, IL : Victor Books, 1983-c1985, S. 1:36-37