If Eugene Peterson is correct that "the word 'sinner' is a theological distinction ... and not a moralistic judgment", then let's consider the implications of that for our understanding of the gospel.
(Read Romans 1:18-2:4)
Notice that Paul makes a clear connection between the loss of knowledge of God and increasing depravity.
In verse 21, we see Paul say "For although they knew God, they neither glorified him as God nor gave thanks to Him ..." In verse 25, "They exchanged the truth of God for a lie", and in verse 28 "Furthermore since they did not think it worthwhile to retain the knowledge of God ..."
All these references show that as we lose our knowledge of God our level of depravity increases.
If the word "sinner" is a theological distinction, then Peterson says "sin" is "separation from God". If this is true, then the cure for sin is growing nearer to God through intimate knowledge gained through His word as mediated by the Holy Spirit.
So instead of looking at behavior as the problem, we should see that lack of knowledge is the problem and it is not only the folks described in chapter 1 who are affected.
Look at 2:1, "You therefore have no excuse you who pass judgment on someone else, for at whatever point you judge the other, you are condemning yourself because you who pass judgment do the same things." Ouch!
So Paul's strategy is to show how everyone is a "sinner" separated from God, and then to show how everyone can come to know God and draw close to Him again.
What do you think about this? Look at the list Paul gives in chapter 1. Do you see any of these tendencies in yourself? If so, what does that say about all the other "sins" on the list? Are any of them ultimately worse than any other? Or are all of them equally descriptive of being separated from God?