Why does Paul do the evil which he hates?

Romans 7:15–17, Romans 7:17, Romans 7:21

Paul often does not even recognize himself as an upright servant of the God of his fathers: For I do not understand my own actions. For I do not do what I want, but I do the very thing I hate (Romans 7:15). Where does this tension between his love for God and his sinful actions come from? Paul’s shock when taking note of the sin in his life can be attributed to the fact that he respects the law, whose commands differ from his actions: Now if I do what I do not want, I agree with the law, that it is good (Romans 7:16). That is how Paul becomes aware of the power of sin in his own life: So now it is no longer I who do it, but sin that dwells within me (Romans 7:17). The apostle is very much aware of this strange influence in his life. A virus is active in his life and apparently, he has no protection against it. Yet Paul does not write this as an excuse, as though he bears no responsibility for his own actions. After all, it is he himself who commits them. He writes this to make clear that life under the law is not the definitive deliverance from sin and from death, regardless of how good the law is. The righteous Pharisee, Saul, consciously becomes aware of the same power of sin that reigns, unnamed, elsewhere in the Gentile world. Both parts of the sentence in Romans 7:21 therefore constitute the reality of Paul’s life: So I find it to be a law that when I want to do right, evil lies close at hand.¹