Ok, I’ve arrived at the most disputed passage of the Bible, Genesis 6:1-4. Theologians and commentators have differed over this passage for a long time (regarding the identity of the sons of God in v.2), and there are smart guys on both sides of it. Technically, my commentary presents three sides, or views. I would try to explain it myself, but I think I’d be better off letting Dr. Constable outline it all:

There are three major views about the identity of the sons of God.
1. They were fallen angels who married women. Arguments in favor of this view follow with responses.
a. The term “sons of God” as it occurs here in Hebrew refers only to angels in the Old Testament (Job 1:6; 2:1; 38:7; et al.). Response. Angels do not reproduce (Matt. 22:30).
b. 2 Peter 2:4-5 and Jude 6-7 appear to identify angels with this incident. Response. There are no other references to angels in the context here in Genesis. These New Testament passages probably refer to the fall of Satan.
c. If God could impregnate Mary, spirit beings may be able to do the same thing to human women. Response. Spirit beings cannot do everything that God can do.
2. They were godly Sethites who married ungodly women. Arguments in favor of this view follow with responses.
a. The Old Testament often refers to the godly as God’s sons (e.g., Exod. 4:22). Response. This would have to be an exception to the technical use of “sons of God” as a reference to angels in the Old Testament.
b. Moses had already established the concept of a godly line in Genesis (4:26).
c. Sonship based on election is common in the Old Testament.
d. Warnings against marriages between believers and unbelievers are common in the Pentateuch.
3. They were dynastic rulers who married women. Fallen angels (demons) may have indwelt or at least controlled them. Arguments in favor of this view and responses follow.
a. Ancient Near Eastern literature often called kings sons of gods.
b. The Old Testament refers to administrators (e.g., judges) as gods. Response. Scripture never regards them as descendants of deities as pagan ancient Near Eastern literature does.
c. This story is similar to Babylonian antediluvian stories.

From Dr. Constable’s Study Notes

So, does anybody out there want to take a shot at identifying who the “sons of God” are? I tend to think that they are fallen angels, according to the first view (by the way, Dr. Constable leans towards the second view). There are a few things that have pushed me to believe the first view. First of all, Tom Nelson has a great sermon that spends some time dealing with this stuff. You can check it out here, but he doesn’t get into this issue until about 14 min. into the sermon. He makes the point that before Gen. 11, most references to “sons of God” are references to angels. After that, it is usually a reference to Israel. Also, the connection between this passage and 1 Peter 3:19-20, 2 Peter 2:4-5, and Jude 1:6 seem obvious to me. Of course, I’m no scholar when it comes to these things, so I may be missing something here. It just seems like those NT passages are clearly identifying Genesis 6. Does anybody else have any thoughts on this? It’s a great, tough passage, but that’s what makes us look hard at our Bibles and that makes us stronger. The minute we begin thinking we know everything that the Bible has to offer, we begin to cheat ourselves out of knowledge and experiencing God.