Christians have sometimes been accused of shooting their own wounded. In our zeal for God, we can sometimes become impatient and judgmental with those who struggle with sin and doubt. Instead of rejecting them, Jude says, we should have mercy on them—just as Christ had mercy on us when he forgave our many sins. While we must not tolerate or accept sin, we are to love and accept others with kindness and mercy. If you know someone who has fallen away from God, your kindness may be just what is needed to lead them back to God.
(Tyndale House) p 1122