Jude's little letter is a call to arms. As you read Jude, you will readily sense the military tone of the book. Jude, in essence, says that when it comes to "the faith" (that system of doctrine that was handed down from Jesus to the Apostles to the early churches) we must do everything we can to fight for it, i.e. to keep it pure, untwisted, etc. Jude says that false doctrine and false teachings will creep into the church unawares. Jude's message is like that of Paul who warned the Ephesian elders to beware of the wolves in sheep's clothing. The wolves will not spare the flock. If we don't fight for the faith, contend for the faith, there could be generations lost. Jude says this is war, therefore, we must earnestly contend for the faith.