Who Were the Nephilim and Sons of God?
by Rich Deem 
Introduction
There is somewhat of a controversy in Christianity regarding the identification of the Nephilim and sons of God mentioned in the Genesis flood account (Genesis 6:2-4). Are the sons of God the human offspring of the godly line of Seth or angelic beings (demons)? Were the Nephilim a race of giants that existed before and after the flood or is the word just a generic term describing large strong people?
Nephilim and sons of God: Genesis 6
Let's look at the passage in question, in context:
Now it came about, when men began to multiply on the face of the land, and daughters were born to them, that the sons of God saw that the daughters of men were beautiful; and they took wives for themselves, whomever they chose. Then the LORD said, "My Spirit shall not strive with man forever, because he also is flesh; nevertheless his days shall be one hundred and twenty years." The Nephilim were 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. Then the LORD saw that the wickedness of man was great on the earth, and that every intent of the thoughts of his heart was only evil continually. (Genesis 6:1-5)
The passage describes the Nephilim as being "men" twice, using two different Hebrew words. It does not use the Hebrew words used to describe angels ("angels," "cherubim," and "seraphim"). It's pretty obvious from the context that God was not happy about what was going on between the sons of God, the Nephilim, and the daughters of men. Let's go on to examine how other biblical passages use these terms.
Sons of God
Unfortunately, the phrase "sons of God" appears in only five verses from only two books of the Old Testament. Two verses are found in the Genesis 6 flood account. The other three verses are found in the book of Job. From the book of Job, the context clearly indicates that "sons of God" are angelic beings, since they enter directly into God's presence1 or existed before the creation of the earth.2 Although the phrase "sons of God" does not reference human beings in the Old Testament, similar phrases, such as "sons of the Most High" and "sons of the living God" do make reference to godly human beings.3 In the New Testament "sons of God" always refer to redeemed human beings.4 It would be very unlikely that ungodly demons would ever be referred to as "sons of God."
The giants (Nephilim)
The Hebrew word used to describe the Nephilim occurs in only two verses of the Old Testament, one in our passage from Genesis 6 and the other in the book of Numbers.5 From the book of Numbers, we find that the descendants of Anak are part of the Nephilim.6 Since Anak was a Canaanite,7 it would be logical to assume that the Nephilim were human, rather than angelic. The verses tell us little about the people, other than they were strong and tall and lived in fortified cities. Were these Nephilim the same as the Nephilim of Genesis 6? Contrary to the beliefs of many, Nephilim does not describe a race of peoples. In the Bible, races of people groups were designated by their founding male ancestor. So, the Anakim were descendent of Anak. However, the Nephilim are never described as being descended from anybody. The term actually means "giants,"8 being derived from the Hebrew word nephal, which means to "fall upon" or "overthrow," referring to their warlike nature.9 Since the Old Testament describes Nephilim both before and after the flood, if the Nephilim were a race then it would contradict the rest of Scripture, which indicates pretty clearly that there were only eight survivors of the flood.10
Demonic or angelic beings?
Some Christian have speculated that the "sons of God" from Genesis 6 were demonic beings, who had sexual relations with human women, and are now condemned to future judgment.11 However, Jesus made it clear that angels are asexual beings who do not engage in sexual relations at all.12 Since demons are merely fallen angels,13 they would, likewise, be unable to procreate with women. Some apocryphal books, such as the book of Enoch14 and book of Jubilees,15 indicate that the Nephilim were fallen angels. However, these books make some outrageous claims, saying that the giants were 450 feet tall!14
Theological problems as demons
There are a number of theological problems with the idea that the Nephilim were demons. First and foremost, there are no biblical accounts of any demon taking on human form. By nature, all angels are spiritual, non-physical creatures.16 All biblical accounts record only obedient angels appearing to human beings. It is never stated that angels have the power to take on human bodily substance (which would be required in order to produce children with human females). Jesus suggested that angles lack the ability to take on human substance, when explaining His bodily resurrection to the disciples:
While they were telling these things, He Himself stood in their midst and said to them, "Peace be to you." But they were startled and frightened and thought that they were seeing a spirit. And He said to them, "Why are you troubled, and why do doubts arise in your hearts? "See My hands and My feet, that it is I Myself; touch Me and see, for a spirit does not have flesh and bones as you see that I have." And when He had said this, He showed them His hands and His feet. (Luke 24:36-40)
So, Jesus indicated that all appearances of angels were not bodily appearances, but merely visual apparitions. If you were to try to touch an angel, your hand would just go through the apparition. Such a manifestation would be incapable of impregnating a human female.
If demons did have the ability to produce offspring through intercourse, one would expect that this would be the major way in which demons would attempt to take control of the human race. Instead, one finds that demons can use only deception17 or possession18 as ways to attempt to thwart the ministry of Christ.
Conclusion 
Since the Bible indicates that angels are asexual beings, it makes sense that they could not be the "sons of God" who produced children with the "daughters of men." The best interpretation is that the "sons of God" were men who were descended from Seth, who followed the Lord for a time (in contrast to the line of Cain, which produced the "daughters of men").19 However, right before the flood, even the "sons of God" took wives among the line of Cain, and, therefore, became corrupted themselves through their unbelieving wives. This is one of the reasons God determined to destroy the entire human race, except for the eight people who still followed the Lord (Noah and his extended family).
Genesis 6 also describes the Nephilim, who were the corrupt strongmen of their time, notorious for their violent exploits (Genesis 6:4). These men were probably also descendants of Cain, who were terrorizing the peoples and represented at least part of the group whose thoughts were "only evil continually." The Nephilim that were described after the flood were also evil strongmen, but not related to those pre-flood people, since they were all destroyed in the flood.