The principle being talked about here is God’s law vs the law of sin. It’s kind of like that image of having a angel on one shoulder and a devil on the other, each trying to persuade you to do things their way. Paul went on to say, “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.” (Romans 7:22-23) These two diametrically opposed laws are constantly at war within us…it’s just a matter of who we listen to or not…but as Romans 6:16 warns us, “You are slaves to the one whom you obey.”