The book of Jude is quite disturbing in its main content: False Teachers. I say disturbing because of what Jude writes:

Jude 3,4:- Beloved, although I was very eager to write to you about our common salvation, I found it necessary to write appealing to you to contend for the faith that was once for all delivered to the saints. For certain people have crept in unnoticed who long ago were designated for condemnation, ungodly people, who pervert the grace of our God into sensuality and deny our only Master and Lord, Jesus Christ.

It’s quite a severe warning if he should have to forego addressing salvation to instead speak about these ungodly people. Jude continues on to tell of the fate of those whom, in days gone by, have not believed, nor kept Gods’ Authority.
There is a positive note within the letter though, with Jude encouraging the readers to persevere

Jude 20-23:- But you, beloved, build yourselves up in your most holy faith; pray in the Holy Spirit; keep yourselves in the love of God, waiting for the mercy of our Lord Jesus Christ that leads to eternal life. And have mercy on those who doubt; save others by snatching them out of the fire; to others sow mercy with fear, hating even the garment stained by the flesh.

This is still a really tough task to fulfill, at least without the grace of God and the constant help of the Holy Spirit…

The doxology that Jude uses is just so lovely

Jude 24,25:- Now to him who is able to keep you from stumbling and to present you blameless before the presence of his glory with glorious joy, to the only God, our Saviour, through Jesus Christ our Lord, be glory, majesty, dominion, and authority, before all time and now and forever. Amen.

I can see why it’s used so often at the closure of services.