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

1:16 These are murmurers, complainers, walking after their own lusts; and their mouth speaketh great swelling words, having men's persons in admiration because of advantage.