Today's Christianity doesn't want anything but to be happy. It wears the facade of righteousness and ignores the fact that each and every Christian is a dirty rotten sinner. Because of this, most of Christianity must ignore the Psalms.
Take Psalm 22:6 "But I am a worm and not a man, scorned by mankind and despised by the people. All who see me mock me; they make mouths at me; they wag their heads;" What self-righteous Christian would ever let these words pass from his mouth believing it was about him? None. No person thinks that he or she is a worm and not a man.
Thus the Holy Spirit must preach it into our hearts. He must convict the world and each of us of sin through the preaching of God's Law. He must bring us to a realization that we aren't righteous people, but worms. See the proof in the crucifixion: As Jesus cried out "My God, my God, why have you forsaken me?", we know that he spoke the entire psalm. He cried out these words as a sinner, though he was not one. He died the death of a sinner, felt the condemnation of the Father on behalf of all mankind, and had imputed to him the guilt of all sinners, which declared him a "worm and not a man."
Christ died for worms. He died for sinners. If you cannot say that you are "a worm and not a man," then you don't believe that Christ died for you.
I am a worm and not a man.
But Christ died for this poor worm, and gave birth to a new man who will be made whole on the return of the Lord. He forgave me, and where there is the forgiveness of sins there is also life and salvation.
Read the psalms. Read all the psalms. Know that you're a sinner, and that God has promised mercy and has given it to you through His Son.