For we know that the law is spiritual, but I am of the flesh, sold under sin. (ESV)
One of the things that I love about the Bible is that it does not sugar coat things. If you look at all of the heroes of the faith you will find men and women with serious flaws. Many people think that men fabricated the words of Scripture. If that were so, then the likelihood is you would not make the superstars of the faith to have such terrible weaknesses.
Consider some of the great heroes of Scripture. David was known as the apple of God's eye. He also committed adultery and murder. Moses led the people of Israel through the desert. His disobedience kept him out of the Promised Land. Jonah had to be punished by being eaten by a large fish before delivering a message to the land of Ninevah.
The heroes of our faith are real. They are flawed. The Apostle Paul is probably my favorite biblical figure, other than God of course! Paul was used by God to proclaim the Gospel all over the known world. He was used by God to raise people from the dead. To me one of the greatest things about Paul is found here in Romans 7. Paul himself struggled with sin. Just like you. Just like me.
Paul recognizes that the law is spiritual. It is holy. It proceeds directly from God. However, Paul himself is not naturally holy, or spiritual. He is by nature of the flesh. He describes himself as being "sold under sin." That does not mean that he is not a Christian, but it does mean that he has to fight the control that sin wants to wield over his body.
Are you tired of trying to be a superhero Christian? Do you feel defeated because sin is such a temptation for you? You are in good company. God's heroes are flawed. Just like Paul. Just like you. Rely on the strength that only Jesus Christ provides.