In Genesis 6:7 we read of God’s gross displeasure with the wickedness of men: “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.’”
Just prior to this announcement there is a statement that has caused quite a lot of speculation. “Now it came to pass, when men began to multiply on the face of the earth, and daughters were born to them, 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.… 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” (Genesis 6:1-4).
What does this mean? Who were the “sons of God”, and where did they come from? Some have guessed that these were a group of angels or heavenly beings who, because of this unique sin, were confined (cp. 2 Peter 2:4; Jude 6). The theory goes that these beings lusted for and ultimately mated with human women. The “mighty men” that resulted from these unions are held up as proof that something “extra-earthly” had occurred.
There are two major problems with this view. First, this view ascribes human sexual desire to heavenly beings. There is nothing in the Scriptures that would support this conclusion. All we know of angels is that they “neither marry nor are given in marriage” (Matthew 22:30). Second, although the term “sons of God” did refer to angels in the Old Testament (Job 1:6; 2:1; 38:7), this view diminishes the uniqueness of the virgin birth of Jesus. His case alone stands out as one in which a child was born by some means other than by natural conception (Matthew 1:23; Luke 1:27, 34).
What is the answer then? A key verse is Genesis 4:26: “… then began men to call on the name of the Lord.” It seems that as human history began to unfold, some men began to make the conscious choice to follow God, and others didn’t. Those who “called on the name of the Lord” would have been known — then, as now — as the “sons of God”. But as time went on, even these men began to be corrupt (including their marriages to wicked mates). Finally, they also were so full of sin and the corruption grew so bad that “it repented the Lord that he had made man on the earth, and it grieved him at his heart” and only Noah “found grace in the eyes of the Lord” (Genesis 6:6-8).