Overview
Jude tells us that there is no new revelation or doctrine. God has completed His saving work. False teachers, introducing new doctrine or belief have been punished in the past and will be judged in the future.
Christian life is to be based only on Scripture itself.
Author
Unlikely to be the apostle Jude and generally accepted to be the half-brother of Jesus and brother of James. Referred to in 1st Cor 9.5 where the "brothers of the Lord" took their wives along on missionary journeys.
Time of Jude
Around AD 65-70