The Apostle Paul had been "Justified" during the episode on the "Road to Damascus". Jesus the Christ confronted him. Paul accepted him as his personal Savior giving up his persecution of the Christians. By accepting Jesus, Paul was made right with God.
He then began his journey of "Sanctification". He was one of the greatest teachers of all, yet he really struggled. Here is an example of what he had to say about it.
The Apostle Paul laments in the 7th chapter of his letter to the Romans (NIV)... 15 I do not understand what I do. For what I want to do I do not do, but what I hate I do. 16And if I do what I do not want to do, I agree that the law is good. 17As it is, it is no longer I myself who do it, but it is sin living in me. 18I know that nothing good lives in me, that is, in my sinful nature. For I have the desire to do what is good, but I cannot carry it out. 19For what I do is not the good I want to do; no, the evil I do not want to do—this I keep on doing.
