Struggling with God's Injustice (Job 31:1-40)

Job is one who has suffered, but he is not someone that we would say is a champion.  He is a man who continually rests in his righteousness while wondering how God can make such a righteous man suffer.  We can chuckle and Job, judge Job, and point out Job’s problems.  However, we still have not asked the deeper question: why is this book in our canon?  What can Job’s suffering and self righteous speech teach us about our Christian walk, our bent, and our failure to see the gospel?