Jude 1:3 "Beloved, while I was making every effort to write you about our common salvation, I felt the necessity to write to you appealing that you contend earnestly for the faith which was once for all handed down to the saints."
Hell is described by Jude as a dark place (1:6, 1:13) Jesus called the darkness of Hell "outer darkness" in Matthew 25:46. Jude then explains hell as a destructive place through the imagery of fire, as seen in Jude 1:7,23. Jesus too refers to the details of unquenchable and everlasting fire burning in both the holding place of unbelievers called hades or Hell and the eternal place of punishment called "The Lake of Fire" or also by the same name "Hell" in Mark 9:43 and Matthew 18:18.
To intensify his already strong warnings, Jude thirdly mentions that hell is demonically infested and reinforces this frightening imagery through the Devil's conflict with Michael the Archangel here on earth and some of the various fallen angels chained in reserved judgment. (1:6,8).
The specific mention of fallen angels in Jude 1:6 matches with what we read of them in 2 Peter 2:4 "For if God did not spare angels when they sinned, but cast them into hell and committed them to pits of darkness, reserved for judgment." Also too, Jesus refers to Hell as having been prepared for "The Devil and his angels" in Matthew 25:41. It is quite likely that Jude is quoting Peter's second letter, which may explain why we also see such similarities between Jesus and Jude (not forgetting that Jude wrote under Divine inspiration).
The Bible Knowledge Commentary remarks: "Most commentators, however, assign the date between A.D. 67 and 80. Jude was probably influenced by Peter, who wrote his second epistle about A.D. 67–68. (Peter predicted that false teachers would arise [2 Peter 2:1; 3:3], but Jude stated that they have “slipped in among you” [Jude 4].)"
Instead, I want to focus the reader's attention on the underlined phrase "holy ones". Biblical passages such as Deuteronomy 33:2; Daniel 7:10; Matthew 16:27 and Hebrews 12:22 use this term to refer to the angels that comprise the heavenly court of God's glory and majesty.
Today we considered three important reasons for the angelic realm being mentioned in the Book of Jude. These three reasons aid in fulfilling the main point of the letter: "To contend for the faith once for all delivered to the saints".
1. Warn of the realities of Hell
2. Encourage with the realities of Heaven
3. Focus attention on Jesus Christ