Don't miss Dan Clendenin's essay on Psalm 100 at The Journey with Jesus:
"The source of confident joy and joyful confidence originates in the fundamental acknowledgement that "the Lord, he is God. It is He who hath made us and not we ourselves; we are His people, and the sheep of His pasture." Turning from divine praise to human dignity, the Psalmist celebrates the good news that we are neither alone nor autonomous. He confesses that God fashioned every single person, and that therefore every human being enjoys an inherent worth that can never be earned or even lost, and that therefore we enjoy His bountiful care. Many people, of course, do not view the world or people this way, and herein lies a great divide between two very different ways of experiencing life itself."