Near the end of a notably harsh letter, Jude encourages the audience to show Mercy is a term used to describe leniency or compassion. God's mercy is frequently referred to or invoked in both the Old and New Testaments. More toward others, even working to save the disobedient from threatened judgment.
Despite all of the anger expressed in Jude and all of the threats of punishment, the book never gives up on the mercy that people experience through Jesus is the Messiah whose life, death, and resurrection are God's saving act for humanity More Christ. Even though the book is so unyieldingly critical of people who might stray or cause others to stray from the Christian traditions the book supports, still at the end, in verses 22-23, there is a command to show mercy to those who are “wavering.” The mercy of Christ, named in verse 21, should motivate people to be merciful to their neighbors.
In addition, people who are disobedient still have a chance to turn things around, and so Jude tells the audience to snatch them “out of the fire.” At the same time, this work needs to be done with care. Jude says that mercy needs to be practiced while “hating even the tunic defiled by” the bodies (or “the flesh”) of those who are disobedient. The point of the image is that those people are so dangerous to authentic faithfulness that they have the power to defile whatever they contact, even their own clothing (cf. v. 8).