The General Epistle of Jude designates its author as “a servant of Jesus Christ and brother of James.” It’s message was for Christians wherever unity was threatened by heretical teaching and where Christian doctrinal and moral standards were questioned.

Jude 1

1:5 I will therefore put you in remembrance, though ye once knew this, how that the Lord, having saved the people out of the land of Egypt, afterward destroyed them that believed not.