What is the believer's actual problem with sin?
The believer's actual problem is not the individual sins they commit, but the production center of those sinful thoughts and actions, which is old Adam, the old nature. Old Adam never stops working, producing greed, envy, and covetousness, so believers never reach perfection in this life.
Les teaches that the believer's real problem is not sins themselves—the things we do that are sinful—but the production center of those thoughts and sins, which is old Adam. Old Adam is the part of us that gets greedy, envious, and covetous. He illustrates that when you see something your neighbor has, old Adam immediately says you have to have it because your neighbor does. Paul warns against living on that plain anymore. Believers never get to a place of perfection because old Adam is never going to quit working on us. Converting the word 'sin' to 'old Adam' opens up this portion of Scripture. Paul also uses the term 'law' to point to a fact of life we have to reckon with.