Genesis 6.1-4 reads in the English Standard Version of the Bible:
1 When man began to multiply on the face of the land and daughters were born to them, 2 the sons of God saw that the daughters of man were attractive. And they took as their wives any they chose. 3 Then the LORD said, “My Spirit shall not abide in man forever, for he is flesh: his days shall be 120 years.” 4 The Nephilim were on the earth in those days, and also afterward, when the sons of God came in to the daughters of man and they bore children to them. These were the mighty men who were of old, the men of renown.
The Nephilim (NEF-i-leem) were giants who lived prior to Noah’s Flood. Yet Nephilim and other words for giants are mentioned in the Bible as having lived after the flood as well. They are mentioned several times in the Pentateuch.
Who were “the sons of God” in Genesis 6.2 and v. 4? This has been a vexing question for millennia. Many Jews and Christians have believed they were angels. In the past several decades, there has been an increasing belief among both academics and many Evangelicals that “the sons of God” in Genesis 6 were angels.
The expression, “the sons of God,” appears occasionally in the Bible, and it does not always refer to the same type of beings. In the book of Job, it refers to angels, and most likely a certain class of angels (Job 1.6; 2.1; 38.7). Sometimes, “the sons of God” in the Bible refers to the mortal people of God (Matt 5.9; Rom 8.14; Gal 3.26). Twice, this expression refers to God’s people at the yet future resurrection (Lk 20.36; Rom 8.19).
There have been three primary interpretations of “the sons of God” in Gen 6.2 and v. 4. Two of these interpretations refer to men, and the other interpretation depicts angels.
First, a fragment of the Dead Sea Scrolls (4Q417) contains the earliest-known reference to the interpretation that “the sons of God” in Gen 6.1-4 are the “children of Seth,” and it condemns them for this rebellion against God. This interpretation says that these “sons of God” were Seth’s descendants who first began to “invoke the name of the LORD“ (Gen 4.25-26), meaning they had faith in God. But they later rebelled against God by taking unbelieving, unrighteous daughters of Cain as their wives. Throughout church history, most Christians have believed in this so-called “Sethite interpretation” of Gen 6.1-4. The main problem with it is that it does not provide an obvious reason why this sexual union resulted in descendants who were giants called Nephilim.
Second, many Jews and Christians have believed in what is called “the fallen angels interpretation” of the sons of God in Gen 6.1-4. They say these sons of God were angels who had sexual relations with women, resulting in their offspring being giants. Many proponents of this interpretation claim these Nephilim were human and angelic.
This second interpretation of Gen 6.1-4 first appears in the Jewish, inter-testamental, non-canonical book of 1 Enoch in an elaborate and extensive scheme in its chapters 6–12. Without citing Gen 6.1-4, it says 200 “angels” made an “oath,” that is, a “curse,” to commit “this great sin” (1 En 6.1-6).
Scholarly proponents of this fallen angels interpretation of Gen 6.1-4 often refer to this reference in 1 En 6.1-6 without also citing the outrageous assertions that follow, “And they took wives unto themselves, . . . And the women became pregnant and gave birth to great giants whose heights were three hundred cubits. These (giants) consumed the produce of all the people until the people detested feeding them. So the giants turned against (the people) in order to eat them” (1 En 7.1-4). Using the standard cubit, which is eighteen inches, this text says these giants were 450 feet tall! That is a tall tale.
1 Enoch repeatedly states that Satan’s name is Azazel. It also says Azazel and angels associated with him “taught the people (the art of) making swords” and other weapons, jewelry, incantations, alchemy, and astrology “as well as the deception of man” (1 En 8.1-3). It says “Azazel . . . taught all (forms of) oppression upon the earth” (1 En 9.6). The angels “lay together with them—with those women—and defiled themselves, and revealed to them every (kind of) sin” (v. 8).
Advocates of this fallen angels interpretation rightly insist that these texts in 1 Enoch are an elaboration of Gen 6.1-12. 1 Enoch often identifies these 200 angels as “Watchers.” It tells about “the Watchers of heaven who have abandoned the high heaven, the holy eternal place, and have defiled themselves with women” (1 En 12.4). Proponents believe that this text means these angels defied God by leaving heaven to commit this evil that corrupted humanity, and that is why they call it “the fallen angels interpretation,” meaning at that time those angels spiritually fell into sin to become sinners. But there is no evidence in the Bible that any angels fell into sin at this time.
Mainstream Judaism strenuously opposed this fallen angels interpretation of Gen 6.1-4. Several ancient, rabbinical sources render “sons of God” (Heb. beni-ha’elohim) in Gen 6.2 and v. 4, respectively, as “sons of the mighty/nobles/rulers/judges.” On the other hand, the JPS, the most popular Hebrew Bible published for Jews today, translates the critical expression beni-ha’elohim (“sons of the gods/God”) in Gen 6.2 and v. 4 as “divine beings.” Some modern scholars regard angels as “divine beings.” But Paul refers to angels as “beings that by nature are not gods” (Gal 4.8; cf. Col 2.18).
Early in my theological education, I was taught this “fallen angels interpretation” of Gen 6.1-4 by my pastor, a graduate of Dallas Theological Seminary. A few years later, I listened to Theodore H. Epp give a series of messages on his popular “Back to the Bible” radio broadcast wherein he refuted this fallen angels interpretation. These messages were reproduced in a booklet I later obtained. I then became convinced, and remain so to this day, that Mr. Epp was right—“the sons of God” in Gen 6.1-4 were men, not angels.
Third, the most compelling treatment of “the sons of God” in Gen 6.1-4, I think, is what is called “the royal tyrant interpretation.” It means famous, ruling men who were kings—perhaps believing Sethites who declined spiritually or from the line of Cain—created harems and thereby conducted human breeding. Concerning the word “took” (Heb. laqach) in Gen 6.2, B-D-B (p. 543) says it here means take “for oneself,” which may suggest the use of force. Regardless, during several generations the progeny of this human breeding experiment resulted in Nephilim, who were giants. Some of these giant men no doubt accomplished amazing exploits that made them famous. They probably were later deified in pagan legends that became the basis of some mythology.
Meredith Kline first proposed this royal tyrant interpretation of Gen 6.1-4. Bruce Waltke adopted it in his commentary on Genesis and modified it by suggesting that those kings were demon-possessed. Although this interpretation denies sexual intercourse between angels and women, Waltke’s convincing version of it makes Satan and his angels the underlying influence of this human wickedness.
Despite strong contrary evidence from the Dead Sea Scrolls, this fallen angels interpretation of Gen 6.1-4 may have been widely believed among Jews of the Second Temple period. Philo, in his book On the Giants (6), adopted it by paraphrasing Gen 6.2, “And when the angels of God saw the daughters of men that they were beautiful, they took unto themselves wives of all of them whom they chose.”
Scholars generally believe the book of Jubilees was written prior to 100 BCE. It adopts this angel interpretation of Gen 6.1-4 as well (Jub. 4.21-22; 5.1-11; 7.21-25). It also says God’s angels are circumcised (Jub. 15.25-27), which, of course, requires that angels have male genitalia. How that was accomplished, since the Bible says repeatedly that angels are spirits, Jubilees does not address. And it says “the angels of the LORD”–God’s angels–took these women as wives.
The Testaments of the Twelve Patriarchs was written in about 150 BCE. It also endorses the angel interpretation of Gen 6.1-4 (Test. Reuben 5.5). And the book Genesis Apocryphon in the Dead Sea Scrolls has a narrative in which Lamech worries that his son Noah is not really his son but the progeny of the “Watchers” in Gen 6.2-4. (“Watchers” appears often in Jewish inter-testamental literature. They refer to angels as in Dan 4.17, cf. vv. 13 and 23, from which the word is probably derived.)
1 Enoch relates likewise. In it Lamech says of Noah, “he looks like the children of the angels of heaven to me; his form is different, and he is not like us. . . . It does not seem to me that he is of me, but of angels” (1 En 106.5-6).
As stated above, in recent decades there has been a resurgence of scholarly support, even among historical-critical scholars, for the fallen angels interpretation of Gen 6.1-4. This is witnessed in many modern commentaries on Genesis. Evangelical scholar Gordon Wenham says in of Gen 6.1-4 in his commentary on Genesis that the LXX and the Latin Vulgate “understood the Nephilim to be the offspring of the ‘angel’ marriages, for in Greek mythology the gigantes were the product of the union of earth and heaven. And this is the way most modern commentators understand the term.” It is surprising that Wenham does not interact with other interpretations of this text.
Bible dictionaries are no different. The popular, one-volume Harper’s Bible Dictionary (p. 696) says the Nephilim are “the offspring of daughters of men and divine beings (Gen. 6:1-4).”
Some Evangelical “prophecy teachers,” as they call themselves, claim the Nephilim offspring of these sexual unions between angels and women were half-human and half-angel. Some further assert that this was a Satanic plot to corrupt the human species.
Furthermore, an increasing number of scholars and pseudo-scientists, as some true scientists allege, believe there are extraterrestrials in our universe. Some identify them as the Nephilim in Gen 6.1-4 and other biblical texts. Some claim the Watchers mentioned in 1 Enoch were extraterrestrials who taught humans various activities.
[See Part 2 for reasons why “the sons of God” in Gen 6.1-4 were men and not angels.]
 These include Targum Onkelos, Symmachus, Samaritan Targum, and Targum Neofiti.
 Meredith G. Kline, “Divine Kingship and Sons of God in Genesis 6:1-4,” Westminster Theological Journal (1962) 187-204. See it online at http://www.meredithkline.com/files/articles/Divine-Kingship-and-Genesis-6_1-4.pdf. Accessed May 10, 2016.
 Waltke, Genesis: A Commentary, pp. 116-18.
 Gordon Wenham, Genesis 1-15, p. 143. I think this is debatable about the LXX.