According to verse 3, Jude was anxious to write about our salvation; however, he changed topics to address contending for the faith. This faith embodies the complete body of Christian doctrine taught by Christ, later passed on to the apostles. After Jude warns of false teachers (verses 4-16), he advises us on how we can succeed in spiritual warfare (verses 20-21). Here is wisdom we would do well to accept and adhere to as we go through these days of the end times.
For a more detailed summary select the link below.
The Book of Jude