John Piper delivered a message at the Desiring God Pastors Conference yesterday entitled, "What is Sin? The Essence and Root of All Sinning" For the full explanation, sermon transcript, and a better exposition, follow the link above! What follows is an overview of Piper's sermon.
Piper points to the book Justification Reconsidered by Stephen Westerholm as part of the impetus for the sermon. In Westerholm's work against the "New Perspective on Paul," chapters two and three deal with sin. The key quote comes from p. 34 of Westerholm's work, "For Paul...it is precisely the 'essential sinfulness' of humankind that requires a salvation based on grace alone, apart from [all] human 'works.'"
Piper then moves forward into an exegetical analysis of Romans 1:18–28, arguing that this passage—perhaps better than any other—demonstrates the bottom, the essence, of sin. This passage gets to the root of depravity. Paul gets at the sin in the heart which produces other sins (cf. Romans 7:8). So, let's look at the high-level overview of the argument.