Romans 7:24-25 (KJV) (24) O wretched man that I am! who shall deliver me from the body of this death? (25) I thank God through Jesus Christ our Lord. So then with the mind I myself serve the law of God; but with the flesh the law of sin.
If we try to live for God in our own strength and abilities, and not by faith, then we are wretched and miserable. Living for God can only be done through faith in Jesus and Him crucified. Paul goes on to tell us, deliverance comes only through faith in Jesus and His death on Calvary. When we try to serve God through our own efforts, then we allow the sin nature to take control, and we have religion instead of salvation, in effect, walking away from God.
(Read 1 Corinthians 15:57)