"These, then, are the two points I wanted to make. First, that human beings, all over the earth, have this curious idea that they ought to behave in a certain way, and cannot really get rid of it. Secondly, that they do not in fact behave in that way. They know the Law of Nature; they break it. These two facts are the foundation of all clear thinking about ourselves and the universe we live in."
C.S. Lewis, Mere Christianity, Book 1, Chapter 1, pg. 8
Paul, the self-proclaimed "chief among sinners," encountered this very dilemma:
I do not understand what I do. For what I want to do I do not do, but what I
hate I do. And if I do what I do not want to do, I agree that the law is good.
As it is, it is no longer I myself who do it, but it is sin living in me. I 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. For 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. Now if
I do what I do not want to do, it is no longer I who do it, but it is sin living
in me that does it. So I find this law at work: When I want to do
good, evil is right there with me. For in my inner being I delight in God's law;
but I see another law at work in the members of my body, waging war against the
law of my mind and making me a prisoner of the law of sin at work within my
members. What a wretched man I am! Who will rescue me from this body of death?
Thanks be to God—through Jesus Christ our Lord!