I humbly disagree with this fallen angel explanation, though I will stop short of arguing over it, because it is not abundantly detailed in the Word and ultimately it may comes down to how one views the Old Testament in macro-sense to the New Testament.
Since I view the OT as having the shadow of what is to come and even a direct contrast from time to time, then I believe that the OT people, while implied to be the sons of God are often never fully addressed as such in the same light as the NT people are because the fullness of the knowledge of God was not yet given at that time. In other words there is an order to things in how God has progressively revealed himself to man in history, not revealing everything at once.
This has been done as the NT tells us for our sakes so that in the fullness of time we might have them as an example.
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For example the OT people are told by Moses that they are collectively, ““Thus you shall say to the house of Jacob, and tell the children of Israel: [SUP][/SUP]‘You have seen what I did to the Egyptians, and how I bore you on eagles’ wings and brought you to Myself. [SUP][/SUP]Now therefore, if you will indeed obey My voice and keep My covenant, then you shall be a special treasure to Me above all people; for all the earth is Mine. [SUP][/SUP]And you shall be to Me a kingdom of priests and a holy nation.’ These are the words which you shall speak to the children of Israel.”
So now in the NT, Peter gives this royal priesthood of all believers its rightful context in Christ Jesus (1Pet. 2).
What was not made clear by direct revelation in the OT is given more light in the NT and we can see in hindsight that this prophetic picturing the OT people’s priesthood was a calling that they continually fell short of because ultimately, they did not have the Holy Spirit or rather the fullness of God’s revelation in the fullness of time had not yet occurred to make the sons of Abraham (by faith) capable of such a life. This is our example, that apart from Christ and His Spirit this priesthood is not possible. Another way to say it would be that through the law, this life was not possible, because the law could not perfect man.
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So it is with this idea of "Sons of God." It is true that this phrase does not abound in the OT but it is nevertheless there as a shadow of what is to be known in the future. The OT people are known as sons of God but continually fail at this calling to live accordingly. And it would seem that scripture reveals this just enough so that they are without excuse but not often enough as to make the people assume that they had obtained it outside of the work of the promised “seed.”
The idea of being a son of God is not fully understood until Christ the true Son demonstrates that true nature and His Holy Spirit is imparted to believers. Nevertheless, God does make this reference in the following ways:
1 God tells Moses to tell Pharaoh that, “Israel is my son, my firstborn. So I say to you, let my son go that he may serve Me.”
2 In 2 Samuel and other passages, God comforts David about his son, saying that “I will be his Father, and he shall be my son.”
3 Later in the Psalms the OT people are referred to as “gods” a passage that Jesus later uses to rebuff the Pharisees’ disdain for Christ having claimed the status as the Son of God.
4 Isaiah makes the reference to God as the everlasting father.
5 Also earlier in Isaiah, God calls the captors of Israel to give them up and to “bring my sons from afar, and my daughters from the ends of the earth— everyone who is called by my name”
6 Likewise in Jeremiah we see the Lord exclaim to the people, “you shall call me, My father; and not turn away from following me.”
7 Later in Jeremiah we see the Lord declare that he is a father to Israel and Ephraim is his firstborn.
8 In 2 Corinthians where Paul quotes an OT passages, possibly the Jeremiah passage, where the Lord declared to Israel, I will be a father to you and you shall be sons and daughters to me.”
9 Hosea in prophetic language about the names of his sons, the children of Israel are given the title as sons of the living God.
10 In Deut 32:8 different manuscripts put it differently but some say that God fixed the borders of the peoples according to the number of the "sons of God," while others say the "sons of Israel."
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Just as he talks about sons of God in the OT, one can see that in this same clouded way, God speaks of this paternal nature in the OT and doesn't often refer to any direct spiritual nature as he says he such things as he will oppose the rebellious Jews as he “opposed their fathers,” relating them to their natural father's behavior. Likewise he would reference the faithful many times to the faithful Jews, their natural fathers.
However, in the fullness of time, Christ now reveals what is really going on when adds more clarity to the language and says to the Pharisees (the unfaithful Jews) you are of your father, Satan. Similarly, we now get this reference as "sons of God" more defined and developed in the NT in the light of the full revelation of God.
I believe that the people of God are known as the "sons of God" in the OT but the point of this title in the OT isn't to reveal the perfect work of God in them, but rather to show us our nature's inability to fill that role through the ages with and without the law and their continual need for a true Son of God from Adam until Christ. The passage in Genesis 6 demonstrates this cohesive story of our failing once more as mankind is prone to be lured by the eyes of the flesh rather than the heart of faith.
In terms of the references about the sons of God in heaven being angels, it would take much longer to say all I wish to say, so I will only comment briefly. In similar fashion to what is described in Job, there is an example of Joshua coming with others (long after he is dead) before the Angel of the Lord with Satan. Satan stands to oppose Joshua who is clothed in filthy garments. In the context of both passages, the Lord speaks first and it is concerning his saints. Satan once again demonstrates his role as the “accuser of the brethren,” as he did with Job. This role is one he did continually in heaven before the Lord according to Revelation.
It is conceivable then that this is not an unusual event in heaven, for the saints to be the point of the conversation or to be brought before the Lord in this manner. Indeed, it is not an open and shut case by any means but it has some biblical merit. Therefore with regard to Gen 6, I am more inclined to believe the explanation that supports the biblical theme of our own propensity to chase after sin, than a violent injustice perpetrated on mankind by fallen angels fornicating with or raping women, that seems to be an arbitrary and untidy piece in fitting with the grand scope of biblical salvation. Instead we know from scripture that the unfaithful yoking of believers to unbelievers has been the source of such falling away (Solomon, Sampson, etc.) and one that is warned against in scripture consistently even into the NT.
Once again, I understand that others have their own belief about such things, but I maintain that God’s plan is coherent and cohesive from beginning to end.
[SUP]“[/SUP]Of the which salvation the Prophets have inquired and searched, which prophesied of the grace that should come unto you, Searching when or what time the Spirit, which testified before of Christ, which was in them, should declare the sufferings that should come unto Christ, and the glory that should follow. Unto whom it was revealed, that not unto themselves, but unto us they should minister the things, which are showed unto you by them which have preached unto you the Gospel by the holy Ghost sent down from heaven, the which things the Angels desire to behold”
This is only my humble opinion and as such should not be perceived as a threat to anyone else’s opinion.
Thank you for reading my llllooonnngggg post.