Genesis 6:1

For many angels of God accompanied with women, and begat sons that proved unjust, and despisers of all that was good, on account of the confidence they had in their own strength; for the tradition is, that these men did what resembled the acts of …

[Moses] called the sons of Seth "sons of God," those who, like the sons of Seth, had been called "the righteous people of God."

As long then as there continued that separation of the lines between them, the seed of Seth, as it sprang from an excellent root, was by reason of its sanctity termed "angels of God," or as some copies have it "sons of God;" and on the contrary the others by reason of their own and their fathers' wickedness and their earthly deeds were termed "children of men." Though then there was up to this time that holy and salutary separation between them, yet after this the sons of Seth who were the sons of God saw the daughters of those who were born of the line of Cain, and inflamed with the desire for their beauty took to themselves from them wives who taught their husbands the wickedness of their fathers, and at once led them astray from their innate holiness and the single-mindedness of their forefathers...From these sons of Seth then and daughters of Cain, as we have said, there were I born still worse children who became mighty hunters, violent and most fierce men who were termed giants by reason of the size of their bodies and their cruelty and wickedness. For these first began to harass their neighbours and to practise pillaging among men, getting their living rather by rapine than by being contented with the sweat and labour of toil, and their wickedness increased to such a pitch that the world could only be purified by the flood and deluge.

God, when He had made the whole world, and subjected things earthly to man, and arranged the heavenly elements for the increase of fruits and rotation of the seasons, and appointed this divine law-for these things also He evidently made for man-committed the care of men and of all things under heaven to angels whom He appointed over them. But the angels transgressed this appointment, and were captivated by love of women, and begat children who are those that are called demons; and besides, they afterwards subdued the human race to themselves, partly by magical writings, and partly by fears and the punishments they occasioned, and partly by teaching them to offer sacrifices, and incense, and libations, of which things they stood in need after they were enslaved by lustful passions; and among men they sowed murders, wars, adulteries, intemperate deeds, and all wickedness. Whence also the poets and mythologists, not knowing that it was the angels and those demons who had been begotten by them that did these things to men, and women, and cities, and nations, which they related, ascribed them to god himself, and to those who were accounted to be his very offspring, and to the offspring of those who were called his brother), Neptune and Pluto, and to the children again of these their offspring. For whatever name each of the angels had given to himself and his children, by that name they called them.

And it came to pass when the children of men had multiplied that in those days were born unto them beautiful and comely daughters.

When men multiplied on the earth, the angels of heaven came together with the daughters of men. In some copies I found "the sons of God."

And it came to pass when the children of men began to multiply on the face of the earth and daughters were born unto them, that the angels of God saw them on a certain year of this jubilee, that they were beautiful to look …

And when men began to multiply on the earth and had daughters, the sons of God saw the daughters of men that they were fair; and they took wives for themselves of all whom they chose.

And it came to pass, when men began to multiply upon the face of the earth,....

When men began to multiply - It was not at this time that men began to multiply, but the inspired penman speaks now of a fact which had taken place long before. As there is a distinction made here between men and those called the sons of God, it is generally supposed that the immediate posterity of Cain and that of Seth are intended. The first were mere men, such as fallen nature may produce, degenerate sons of a degenerate father, governed by the desire of the flesh, the desire of the eye, and the pride of life. The others were sons of God, not angels, as some have dreamed, but such as were, according to our Lord’s doctrine, born again, born from above, Joh 3:3, Joh 3:5,Joh 3:6, etc., and made children of God by the influence of the Holy Spirit, Gal 5:6. The former were apostates from the true religion, the latter were those among whom it was preserved and cultivated. Dr. Wall supposes the first verses of this chapter should be paraphrased thus: “When men began to multiply on the earth, the chief men took wives of all the handsome poor women they chose. There were tyrants in the earth in those days; and also after the antediluvian days powerful men had unlawful connections with the inferior women, and the children which sprang from this illicit commerce were the renowned heroes of antiquity, of whom the heathens made their gods.”

- The Growth of Sin 3. דון dı̂yn “be down, strive, subdue, judge.” בשׁגם bāshagām “inasmuch, as also.” The rendering “in their error” requires the pointing בשׁגם beshāgām, and the plural form of the following pronoun. It is also unknown to the Septuagint.

Some authorities suggest that this might be an allusion to the Sons of God who came down to corrupt the daughters of men, resulting in the Nephilim (Fallen Ones) of Genesis 6.