That being said, here is something to consider--
"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..."
This text clearly connects two judgments:
The judgment of angels who sinned, and
The judgment of the ancient world in the days of Noah.
The key interpretive question is: what sin did these angels commit? -- and more specifically, was it sexual in nature?
1. 2 Peter 2:4–5
Peter does not specify the sin explicitly, but he aligns it chronologically with Noah’s time, thus linking the sin of the angels with the antediluvian (pre-Flood) period.
2. Jude 6–7 (parallel passage)
“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;
as Sodom and Gomorrah... having given themselves over to sexual immorality and gone after strange flesh, are set forth as an example, suffering the vengeance of eternal fire.” (NKJV)
This is a crucial interpretive key-
Jude directly compares the angels’ sin to Sodom and Gomorrah’s sexual perversion, which involved going after strange flesh (Greek: σὰρκα ἑτέραν, "different flesh").
Scholars such as Douglas Moo, Tom Schreiner, and Richard Bauckham affirm that Jude is referring to the angelic rebellion in Genesis 6:1–4, where “sons of God” (bene elohim) take human women as wives--interpreted by many Jewish and early Christian sources as angels engaging in sexual relations with humans.
Early Jewish Interpretation
1 Enoch 6–10
An ancient Jewish text widely read in the Second Temple period and quoted in Jude (v. 14–15), 1 Enoch explicitly teaches that angels (the Watchers) lusted after and mated with human women, producing the Nephilim. This text heavily influenced Peter and Jude’s portrayal.
Philo of Alexandria (De Gigantibus §6–7)
Philo also held the view that fallen heavenly beings had sexual relations with women, an interpretation consistent with many Jewish writers of the period.
So--did the angels commit actual, sexual sin?
Yes, according to the contextual flow of 2 Peter 2:4–5, the parallel in Jude 6–7, and the interpretive backdrop of Genesis 6:1–4, the angels who sinned are widely understood to have committed sexual sin by abandoning their proper nature and engaging in unnatural relations with humans.
This interpretation was standard among:
Second Temple Jewish texts (1 Enoch, Jubilees)
Early Church Fathers (Justin Martyr, Athenagoras, Irenaeus, Tertullian, etc.)
Many modern scholars (e.g., Michael Heiser, Richard Bauckham, Larry Hurtado)
I personally value Jewish sources and am not hesitant to engage with the Apocrypha, as well as the customs and cultural background of the Jewish people.
Understanding these elements often sheds much-needed light on the historical and theological context of Scripture.
Shalom.
J.