Author: Jude, brother of James
Subjects: False believers are revealed by their sinful behavior
Jude introduces himself, and then he immediately expresses his concern for "counterfeit believers" (see 2 Timothy 3:8) who are pretending to be Christians but are actually ungodly. Jude makes the point that these false believers are not saved, giving examples from the Old Testament of God's reaction toward unbelievers and sinners.
The examples that Jude gives indicate that the actions of these people is what reveals their unbelief. Jude further describes these people as "waterless clouds" and "trees without fruit."
Jesus Christ also gives this example in the Parable of the Barren Fig Tree, with the character in the story saying, "See here! For three years I have come looking for fruit on this fig tree, and still I find none. Cut it down! Why should it be wasting the soil?" (Luke 13:7)
Jesus is also recorded as saying, "Every tree that does not bear good fruit is cut down and thrown into the fire." (Matthew 7:19)
Regarding these false believers (who are shown to be false believers by their actions), Jude says, "for whom the deepest darkness has been reserved forever." (Jude 1:13) To further emphasize his point, Jude quotes additional scripture of prophecy regarding the judgment that will come on those who have committed "deeds of ungodliness." (Jude 1:14-15)
Jude continues to list examples of sins that these false believers continue to commit, saying that the apostles warned them of these kinds of people. Jude then instructs his audience on how to behave and gives his farewell.
The letter of Jude is a short text addressed to Christians. Jude writes with a concern regarding false believers who are within the church pretending to be Christians. Jude instructs his audience that false believers are revealed by their sinful actions, and his letter appears to be a message to identify and excommunicate these people.
Paul also speaks of this kind of subject in several of his letters: "After a first and second admonition, have nothing more to do with anyone who causes divisions..." (Titus 3:10) "For people will be lovers of themselves, lovers of money...unholy...lovers of pleasure rather than lovers of God, holding to the outward form of godliness but denying its power. Avoid them!" (2 Timothy 3:2-5)
The main subject of this short letter of Jude is how to identify and deal with these counterfeit Christians.