Genesis 6 refers to “sons of God” having relationships with the women of the earth: “When the human beings (האדם; ha’adam) began to increase on the face of the ground, and daughters were born to them, the sons of God (בני אלהים; benei elohim) saw that the daughters of the humans (בנות האדם; benot ha’adam) were beautiful, and they took as their wives any they chose” (6:1-2). Though the identity of these “sons of God” is a matter of debate, it is most likely that they were lesser deities who rebelled against the authority of Israel’s God.
In understanding the “sons of God,” the Bible reader has multiple options. Since Scripture sometimes refers to the Davidic king as God’s “son” (בן; ben, e.g., 2 Sam 7:14; Ps 2:7), it’s possible that the “sons of God” in Genesis 6 were royal men who “took women for themselves” (יקחו להם נשׁים; yiqkhu lahem nashim) as an abuse of their power. Others have read these entities as fallen angels, noting the fact that their offspring are called the Nephilim (נפלים)--in Hebrew, “fallen ones.” However, since the “sons of God” are never called “angels” (מלאכים; malakhim), this interpretation goes beyond the textual data.
Based on other biblical appearances of the “sons of God,” it is more likely that these entities are lesser gods over whom the God of Israel has authority. The beginning of Job presents a heavenly court scene in which “the sons of God (בני אלהים; benei elohim) came to present themselves before the Lord” (1:6; cf. 2:1). When God speaks to Job toward the end of the narrative, the Lord refers to the heavenly “sons of God” existing prior to earthly creation. God asks Job, “Where were you when I laid the foundations of the earth… when the morning stars sang together and all the sons of God (בני אלהים; benei elohim) shouted for joy?” (38:7). Since in Job the “sons of God” are divine underlings in the Lord’s entourage, it is best to view the episode in Genesis 6 as an instance of the lesser gods leaving their heavenly realm and taking human women; the sons of God choose to abandon their posts under the Lord and enter the earthly realm. This rebellious divine behavior is met with the subsequent flood (cf. Gen 6:11-13) but, ultimately, the Lord exercises continued authority over such rebellion in the preservation of humanity through Noah.