I'll try to condense this post as much as possible, but I wanted to share a bit of our Sunday night Bible lesson with you.
This is one of those topics in the Bible that you have to read and study for yourself and draw your own conclusion. The conclusion should not be a dividing point amongst Christians, as this is not a matter of eternal security, but it is interesting to study out.
Our pastor is preaching through Genesis right now on Sunday mornings, but he saved this specific topic for in-depth study, which is usually what we do on Sunday evenings.
The scripture text is Genesis 6:1-8 (NKJV). Now it came to pass, when men began to multiply on the face of the earth, and daughters were born to them, that the sons of God saw the daughters of men, that they were beautiful; and they took wives for themselves of all whom they chose. And the LORD said, "My Spirit shall not strive with man forever, for he [is] indeed flesh; yet his days shall be one hundred and twenty years." There were giants 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 in the earth, and [that] every intent of the thoughts of his heart [was] only evil continually. And the LORD was sorry that He had made man on the earth, and He was grieved in His heart. So the LORD said, "I will destroy man whom I have created from the face of the earth, both man and beast, creeping thing and birds of the air, for I am sorry that I have made them." But Noah found grace in the eyes of the LORD.
The key phrase we were looking at was in verse 2 - "sons of God." There are three main thoughts/opinions (and probably more) that exist. 1) Angels took wives of the human race. 2) The sons of God were the sons of Seth who cohabited with daughters of Cain. 3) Possibly kings that were wanting to build harems.
First of all, it is important to notice that all of this happened just before the great flood. If you look at 2 Peter 2:4-5 - For if God did not spare the angels who sinned, but cast [them] down to hell and delivered [them] into chains of darkness, to be reserved for judgment; and did not spare the ancient world, but saved Noah, [one of] eight [people], a preacher of righteousness, bringing in the flood on the world of the ungodly;
Those two verses speak of angels being punished as well as the ancient world but Noah being saved. It appears to be the same time span as Gen. 6. Could these angels in chains of darkness be the ones who took human wives just before the flood?
These angels are spoken of again in Jude 6 - And the angels who did not keep their proper domain, but left their own abode, He has reserved in everlasting chains under darkness for the judgment of the great day;
and verse 7 - as Sodom and Gomorrah, and the cities around them in a similar manner to these, having given themselves over to sexual immorality and gone after strange flesh, are set forth as an example, suffering the vengeance of eternal fire.
Angels marrying and cohabiting with humans would definitely fall under the category of "not keeping their proper domain" and "going after strange flesh." The transition to Sodom and Gomorrah in v. 7 points to the similitude of the sin of homosexuality and what these angels did in Gen. 6. (MacArthur Study Bible note)
And something else to think about. Jesus, our Messiah, had not been born yet. He needed a pure human race to be born of.
Soon after the sons of God took wives, the great flood came. Only Noah and his family survived. The wickedness was great upon the earth, and there was possibly an impure race abounding. God wiped this slate clean when all the earth was destroyed - except Noah and his family. Now there would be no chance that the Messiah would be born of a human race that had been corrupted by fallen angels.
I think I've been convinced that the number one opinion is correct, but I won't argue with you about this, and I certainly encourage you to take a look at all three thoughts and draw your own conclusions. I felt a sense of excitement as we studied through this, and I couldn't wait to share it with you. God's Word is amazing!