It's a small letter with a big punch. The writings of Jude, located close to the end of your Bible, right in front of the book of Revelation, contain two admonitions for Christians. It is vitally important we do not miss these.
First, he addresses the church as a whole with a warning against false teachers. I have to admit to you, the picture in my mind when I think of false teachers is one of some burly brute forcing me to listen to, and be brainwashed by, something other than biblical truth. That isn't always the case. The Bible paints another picture of them in this small letter to the church. Take the time to read Jude, verses 3-16.
In these verses, the false teacher is described in various scenes, such as," they claim authority from their dreams, live immoral lives, defy authority and scoff at the power of the glorious ones." Or look at this description, "these people mock and curse the things they do not understand. Like animals, they do whatever their instincts tell them, and bring about their own destruction." Jude even says when you try to be in fellowship with the false teacher, "they are like a dangerous reef that can shipwreck you."
All of this tells me Satan is no dummy. He uses his tricks and schemes to infiltrate the lives of those in the church and Jude's warning is that we must be prepared for them. He says to us, "Look, the Lord is coming with thousands of his holy ones. He will bring the people of the world to judgment. He will convict the ungodly of all the evil things they have done in rebellion and of all the insults that godless sinners have spoken against him." Ok Jude, I get it. These rebels and sources of untruth will be among us, and God is going to see that they get what's coming.
I hope we are not thinking that any of the brethren that disagree with us are automatically rebellious false teachers. God has made provisions in his plan for there to be unity in the midst of diversity. And just because someone expresses an opinion that is not the same as yours, doesn't mean they are out to wreck the church. That's why Jude made his second point.
He issues a plea for God's people to remain faithful. Look at verse 20. "But you, dear friends, must continue to build your lives on the foundation of your holy faith. And continue to pray as you are directed by the Holy Spirit. He makes a further encouragement to live in ways that God's love can bless you. Show mercy to those with wavering faith.
Then his closing admonition. And now, all glory to God, who is able to keep you from stumbling, and who will bring you into his glorious presence innocent of sin and with great joy. All glory to him, who alone is God our Savior, through Jesus Christ our Lord. Yes, glory, majesty, power, and authority belong to him, in the beginning, now, and forevermore. Amen"
May God strengthen us with discernment when dealing with workers of evil, and may we always hold to his truth which has been graciously entrusted to us. ALL authority belongs to him. Amen.