It is most likely that Jude is the physical brother of Jesus. In the Gospels we know that Jesus’ family did not believe in Him. After His resurrection, however, both His brother James and His brother Jude became His disciples and prominent leaders in the church. In this letter, Jude is writing to the church to fight against the false teaching that was filtering into their ranks. There are great similarities between Jude and 2 Peter, as both letters are speaking very harshly and firmly against false teachers. The believer is called to fight for the faith and not be misled.