Pretty much sums it up, doesn't it?  The above verses are from Psalm 50 (the latter part of vss. 7 and 21 NAS).  Let's face it:  many (I believe the overwhelming majority of) Christians are disappointed in God.  Wondering why their lives continue in defeat over the same sins. Wondering why God doesn't care.  Why He didn't act. Why His power is not manifested in their lives.