(1) And it came to pass, when men began to multiply on the face of the earth, and daughters were born unto them, (2) That the sons of God saw the daughters of men that they were fair; and they took them wives of all which they chose. (3) And the LORD said, My spirit shall not always strive with man, for that he also is flesh: yet his days shall be an hundred and twenty years. (4) There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown. King James Version Change your email Bible version
“Sons of God” cannot refer to angels in Genesis 6:4 because it warps God's ultimate plan for humanity's salvation. He states His purpose in Genesis 1:26, “Let us create man in Our image, according to Our likeness.” In other words, God is reproducing Himself! Human beings are not fashioned after the angel-kind but after the Godkind!
Notice how God introduces His earlier creations: “Let the earth bring forth grass . . .” (Genesis 1:11); “Let the waters abound with an abundance of living creatures . . . (Genesis 1:20); and “Let the earth bring forth the living creature according to its kind . . .” (Genesis 1:24). But when He begins to create man, He reveals that He brought humanity from Himself. While Adam was made of the dust to be physical, his origins in terms of “image” and “likeness” came directly from God. Because of this vast difference, God commands that men—His potential spiritual children—“have dominion” over all living things on the earth (Genesis 1:26, 28).
God is reproducing Himself. The concept of angels reproducing themselves through interspecies marriages with humans denies the very gospel of the Kingdom of God, the good news that God offers human beings the opportunity to join His Family and inherit all things. Angelic/human hybrids insert an alien element into the plan of God, which He would never allow to confuse matters.
In addition, while angels are called “sons of God,” they do not have the potential humans have. They were created, not as potential members of the God Family, but as servants.
It is plain that God never intended that angels, though presently far exceeding humans in intellect, power, and wisdom, be born into God's Family and inherit the Kingdom of God (Hebrews 2:5). The Bible consistently shows them in the form of mighty servants who carry out God's will and help Him fulfill His purpose. As the author of Hebrews says, while currently lower than the angels, human beings will one day rise to be greater than they, crowned with glory and honor and possessing power over the works of God's hands (Hebrews 2:6-8).
— John Reiss