"When men began to multiply on the face of the ground, and daughters were born to them, the sons of God saw that the daughters of men were fair; and they took to wife such of them as they chose. Then the Lord said, "My spirit shall not abide in man for ever, for he is flesh, but his days shall be a 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. These were the mighty men that were of old, the men of renown.
"...And the Lord was sorry that he had made man on the earth,
and it grieved him to his heart. Gen 6:1-4,6...
Transliteration: šēm
Gesenius' Hebrew-Chaldee Lexicon - Sons of men (Gen. 6:4) --- "famous men"
Outline of Biblical Usage : name, reputation, fame, glory,
My research says that "the sons of God" refer to those descendants of Seth who trusted in the Lord but whose children intermarried with women descended from Cain. The marriage union was not with angels but one consummated between the godly and ungodly families of men. Angels neither marry nor are given in marriage so that the verse hardly applies to them.
This was with the generation of Noah just prior to the flood where God speaks of his judgment indicating that he is displeased with the wickedness of men and therefore decides to destroy that entire generation - with the exception of Noah's family.
This is a great "shadow" of what of the next and final destruction of all unbelievers at the end of this age will be like but with fire this time instead of water. Sodom and Gomorrah is the "mini-foreshadow" of that Last Day event.
This "flood" was due to "believers intermarrying with "unbelievers" just as the Samaritans had done at the time of Jesus; Jews intermarried with the Assyrians while they were in captivity. Then the "devout" Jews of Judah considered the Samaritans to be "defiled."
I also see our present day status of our so-called "Christian" country as being the same as the Noahadic flood conditions of Noah's time as well as the same conditions that Lot was under with the Sodomites of Sodom and Gomorrah that was destroyed for their ungodliness. Is not our country just like those times? I think so. God's "church" is in many ways now barely recognizable as a "true Christian church."
2 Corinthians 6:14-16..."Do not be bound together with unbelievers; for what partnership have righteousness and lawlessness, or what fellowship has light with darkness? Or what harmony has Christ with Belial, or what has a believer in common with an unbeliever? Or what agreement has the temple of God with idols? For we are the temple of the living God; just as God said,
“I will dwell in them and walk among them;
And I will be their God, and they shall be My people.
Yes amen