Here is a good academic presentation of the controversial passage of Gen. 6.4. This section is immediately preceded by genealogies in Gen. 5. My view is Human Hybridization: Two inbred lines combine to produce superior progeny. I believe this is a natural and true phenonomen that was observed for the first time in Gen. 6.

Also, if we (Christians) think of what Jesus said in regards to our future, it makes sense to see potential human angels sinning: but those who are considered worthy to attain to that age and to the resurrection from the dead neither marry nor are given in marriage, for they cannot die anymore, because they are equal to angels and are sons of God, being sons of the resurrection (Lu. 20.35-36). The redeemed O.T. saints had to have a certain hope of reward (or what was the point of faithfulness?) which they could sin against in their weaker moments. Other, superficial followers of these “sons of God” might sin defiantly and choose partners outside the covenant community. This is how I view this tragedy.

Here are some verses from the Apostles warning against O.T. myths. What were these exactly? The myths need identifying or the message is lost. Can anyone identify other myths that would have been in circulation during the time of the Apostles for them, in several places, to warn us? I think Gen. 6.4 and the previous genealogy is the best candidate for these warnings. These Apocyrphal (Enoch, Jubilees) accounts contain fantastical additional information that should alert us to their falsity.

nor to devote themselves to myths and endless genealogies, which promote speculations rather than the stewardship from God that is by faith (1Tim.1.4)

not devoting themselves to Jewish myths and the commands of people who turn away from the truth. (Ti.1.14)

Have nothing to do with irreverent, silly myths. Rather train yourself for godliness (1Tim. 4.7)

But avoid foolish controversies, genealogies, dissensions, and quarrels about the law, for they are unprofitable and worthless (Ti.3.9)

and will turn away from listening to the truth and wander off into myths. (2Tim. 4.4)