Sons of God Never Refers to Angels

Angels, like Gabriel, are almost universally misunderstood to some degree or another. This is not to say that everything is known about them by anyone, but that what is thought to be known is most often wrong. Adding to the confusion is that the word simply means "messenger" and sometimes humans are called "angel". What I will be speaking of are the beings who are like Gabriel and the heavenly host of Luke 2.
One of the issues I encounter on a regular basis is the idea that the phrase "sons of God" is a reference to celestial angels. This simply is never the case in the Bible. I will present arguments to show that the phrase "sons of God" only ever refers to faithful humans.
== I. Examining the Verses in Question ==
===Genesis 6:1-4===
And it came to pass, when men began to multiply on the face of the earth, and daughters were born unto them, That the sons of God saw the daughters of men that they were fair; and they took them wives of all which they chose. And the Lord said, My spirit shall not always strive with man, for that he also is flesh: yet his days shall be an hundred and twenty years. There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown.
In Genesis 4 we have the murder of Abel followed by the descendants of Cain. Then, in Genesis 5, we have the line of Seth. 
Cain's line is focused on physical things, metal working, mechanical instruments, building cities, and tending to animals. Great progress was made by Cain's line, but the focus was on self not on God. We see this exemplified in Lamech who murdered a man and instead of feeling remorse and being penitent, he brags about it and lays claim to protection greater than that of Cain.
In Contrast, we see Seth's line as starting off as righteous. This is exemplified in Enoch who walked with God. However, we know that by the time of Noah, Seth's line had become wholly corrupted somehow so that only Noah found favor in God's sight.
Genesis 6:1-4 is the explanation of how that happened. When men (that is Cain's line) began to multiply, the sons of God (the faithful descendants of Seth) saw the daughters of men (Cain's descendants) and they began to intermarry. The focus here is on the physical beauty and the corruption that focusing on the physical brings. This is Moses writing of the history of man to the Israelites as they wander in the wilderness for those 40 years. That warning against addiction to the physical is echoed all the way through the Bible until the very last book of the NT is written. It is when the faithful men, the sons of God, started to focus on fleshly things rather than spiritual (Romans 7-8), that they were corrupted.
Note that when the sons of God reproduced with the daughters of men, they reproduced after their kind...men.
===John 1:12===
But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name:
I wanted to save Job for the last because its the hardest for many to swallow. Instead, I want to completely establish the idea of the sons of God in the New Testament as faithful men
Here in John 1, the apostle writes that those who have faith have the ability to become "sons of God". I've never heard anyone argue that faith empowers men to become celestial angels like Gabriel. What John is teaching is that faith, as a prerequisite to salvation, gives humans the ability to do all that God requires of us to be saved: namely repent, confess our faith in Christ to others, and be immersed in water into Christ. The sons of God, then, are Christians. A theme carried throughout the entire New Testament.
===Romans 8:14, 19===
For as many as are led by the Spirit of God, they are the sons of God.
For the earnest expectation of the creature waiteth for the manifestation of the sons of God.
Without getting into too much of a tangent (see my commentary on Romans 8), Paul is saying that those who are led by the Spirit of God (have conformed their lives to the Word in contrast to the world), are Christians, followers of Christ, and adopted children.
===Philippians 2:15===
That ye may be blameless and harmless, the sons of God, without rebuke, in the midst of a crooked and perverse nation, among whom ye shine as lights in the world;
Paul is not telling the Philippians that they should be blameless, harmless angels without rebuke. He is saying they should exemplify what the adopted children of God are supposed to be in an otherwise wicked world. He is directly referring to Christian men at Philippi and calling them sons of God.
===1 John 3:1-2===
Behold, what manner of love the Father hath bestowed upon us, that we should be called the sons of God: therefore the world knoweth us not, because it knew him not. Beloved, now are we the sons of God, and it doth not yet appear what we shall be: but we know that, when he shall appear, we shall be like him; for we shall see him as he is.
John again uses the phrase "sons of God" and this time he includes himself directly in that category by referring to "we". Definitely faithful humans here.
So what about Job, then?
=== Job 1:6; 2:1 ===
Now there was a day when the sons of God came to present themselves before the Lord, and Satan came also among them.
Again there was a day when the sons of God came to present themselves before the Lord, and Satan came also among them to present himself before the Lord.
In this familiar scene, the sons of God come to present themselves before Jehovah God and Satan comes in among them. There are two possible scenarios here.
1) Faithful worshipers of God, of which Job is one, come before God (though physically still on Earth) to worship Him and Satan (also on Earth) comes in among them as he always does looking for a way to tempt them away from God. God knows Job's heart and singles him out as an example of the faithful (and who knows, diverts Satan's attention away from a weaker man, saving that man as well?). Satan takes every physical thing away from Job save his wife and then Job in the next chapter is right back presenting himself before Jehovah, worshiping Him faithfully.
2) The more popular scenario, and one that makes no sense to me whatsoever, is the idea that the "sons of God" are angels in Heaven who present themselves (meta?)physically in front of the Throne of God to worship Jehovah. Remember, at this point, according to the mythos Satan has already rebelled and been cast out of Heaven. Yet somehow his thoroughly evil self is allowed back into Heaven, allowed to walk among the (other?) angels and challenge God yet again among them.
If 2 is the case, my question is why? What purpose is served in the book of Job to mention the sons of God (if this is a reference to angels) at all? They don't take part in the story of Job. They are nothing more than a passing reference, extraneous settings for the scene.
God does nothing without purpose. Jesus taught that every jot and tittle of the OT was important (Matthew 5:18). Scenario 2 is pointless in the way it is presented. Scenario 1 is in perfect harmony with the rest of the Biblical narrative and does not put Satan in Heaven where I believe he never was and where even the mythos of him being cast out for his rebellion finds conflict with him suddenly being back there.
===Job 38:7===
When the morning stars sang together, and all the sons of God shouted for joy?
The last objection is usually found here in Job 38:7 where Jehovah is recounting to Job all the wondrous things God had done and who was Job to question God. It is assumed that the phrase "morning stars" and "sons of God" both are references to angels. My question is again "why?" What in the immediate or remote context makes this demand? The only other references to "morning star" are Lucifer (daystar) and Jesus, both kings. In Genesis (1:16-18), the sun, moon, and stars are associated with authority. Stars used metaphorically in scripture always refers to some kind of authority figure, kings, princes, or ruling councils.
Within the timeline of Job 38 we have a natural flow from Creation (38:4-6) to the Flood (38:8f). If we use the correct understanding that the morning stars are the earlier rulers of men on the earth, that the sons of God are the faithful of the line of Seth before the Flood, then we find consistency throughout scripture instead of something that is only in this one instance a complete aberrant use of the phrase. It also further supports and harmonizes with the more consistent scenario 1 in Job 1-2. 
== II. Children of God ==
A brief note about the phrase "children of God" should be made, first because it will alleviate any confusion about angels being children of God, and second because it will actually further establish the premise.
The phrase "children of God" is ever only used explicitly in the New Testament and it is a reference to Christians. However, in the Old Testament, the nation separated for the purpose of fulfilling the promise to Abraham, physical Israel, were called God's people and "my children". In both cases, however, the Bible is only ever talking about humans.
== III. Conclusion ==
Mankind has done quite an amazing job of mucking up our understanding of scripture, and specifically of celestial angels. Most people's understanding comes from works of fiction: Dante's Inferno, Milton's Paradise Lost, or a host of movies and television (e.g. Supernatural). The art of the Renaissance brought even more misunderstanding to the topic. Add to that the extreme error of millennialism in all its forms, and its no wonder the topic of angels is so understood so poorly by man today. Furthermore, those gross misunderstandings lead to further misunderstanding and corrupt interpretation of a host of scripture, books like Revelation, Daniel, and the rest of the books of prophecy most.
If we understand angels, especially Satan, in light of the millennialist and fictional terms as beings from Heaven who sinned and fell or were cast out and had sex with humans, then our view of Heaven and Creation becomes corrupted. Heaven is a place where the very idea of rebellion can exist, and sin can happen. That's not the picture of Heaven we get from scripture, and its not a Heaven I want any part of.
This is the danger of bringing in external understandings to the scripture, to inform and interpret scripture. It is uninspired and corrupting, just like the influence of the line of Cain on the line of Seth. We diminish greatly our ability to reach the lost who look upon these fantastic images in the Bible (and in media) and see gross inconsistency and chaos. Worse, we harm those weaker in the faith who are challenged by those on the outside with these inconsistencies created by external sources.
As students of the Word, we must recognize that the Bible should be our only guide for Truth (2 Tim. 3:16-17) about angels, about anything. The old saying was to speak where the Bible speaks and be silent where it is silent. Let's consistently apply that to the study and understanding of angels.
In Truth and Love.