Learn to Fight: It's Costly And Agonizing

The spiritual fight Jude calls us to is a fight for "the faith." This is not our personal faith, or trust in Christ, but the content of our faith-- the Gospel itself. When Jude calls us to "contend for the faith" he is emphasizing that

...[T]he defense of this faith will be continuous, costly and agonizing; the cost of being unfashionable, the agony of seeking to express the faith in a way that is really comprehensible to contemporary man. For, granted the once-for-allness of the Christian faith, we must not neglect Dietrich Bonhoeffer's passionate plea in The Cost of Discipleship against the cheapening of Christianity until it becomes a set of propositions assented to, of acts performed, of shibboleths observed, rather than the vibrant, vital personal relationship with Jesus which inflames, invigorate and permeates every aspect political, social and personal life. Michael Green, Tyndale New Testament Commentary on 2 Peter and Jude