Since Psalm 103:20 says angels obey God, then clearly angels can’t sin, that means that the angels that are spoken of in 2 Peter 2:4 aren’t fallen angels, they are people, Numbers 16:30-33 says who those people are.
Psalm 103:19 – The LORD hath prepared his throne in the heavens; and his kingdom ruleth over all.
Psalm 103:20 – Bless the LORD, ye his angels, that excel in strength, that do his commandments, hearkening unto the voice of his word.
Psalm 130:21 – Bless ye the LORD, all ye his hosts; ye ministers of his, that do his pleasure.
The Greek word for “angel” is “aggelos”, an angel is someone sent by God, an angel is a messenger, the Messiah was God’s aggelos (messenger), an angel can be a celestial being or human being, since Psalm 103:20 makes it very clear that angels (celestial beings) don’t sin, then the “angels” in 2 Peter 2:4 must be people.
2 Peter 2:4 – For if God spared not the angels that sinned, but cast them down to hell [Gehenna], and delivered them into chains of darkness, to be reserved unto judgment;
Numbers 16:30 – But if the Lord [God] causes a new thing [to happen], and the earth opens its mouth and swallows them up, with all that belongs to them, and they go down alive into Sheol (the place of the dead), then you shall understand that these men have provoked (spurned, despised) the Lord [God] !
Numbers 16:31 – As soon as Moses stopped speaking, the ground under the offenders split apart
Numbers 16:32 – And the earth opened its mouth and swallowed them and their households and [Korah and] all [his] men and all their possessions.
Numbers 16:33 – They and all that belonged to them went down alive into Sheol (the place of the dead); and the earth closed upon them, and they perished from among the assembly.
The angels that are spoken of in 2 Peter 2:4 are the people that God destroyed in Numbers 16:30-33.
Jude 1:6 talks about the same thing as 2 Peter 2:4, here is a link to my post entitled “Jude 1:6 Is Not Talking About Fallen Angels” that will explain more about Jude 1:4-19
The Bible makes it very clear that angels (celestial beings) don’t sin, here is a link to my post entitled”Angels Don’t Sin” that will prove that none of the angels (celestial beings) sinned. https://bornfromabove7.wordpress.com/2014/09/05/angels-dont-sin/
And here is a link to my post entitled “2 Peter 2:10-12 Is Not Talking About Fallen Angels” that will explain why 2 Peter 2:10-12 is not talking about fallen angels. https://bornfromabove7.wordpress.com/2014/09/06/2-peter-210-12-is-not-talking-about-fallen-angels/