The whole passage (2 Cor. 5:20b-6:10) is great, but I’m just going to link to a few notes I’ve written on the key verse in 2 Corinthians 5:21.
- Wright and Piper on 2 Corinthians 5:21
- English and Greek Ambiguity – 2 Corinthians 5:21
- Becoming Righteous and Becoming Rich
- Righteousness of God Redux
The way you understand the phrase “righteousness of God” will color much of the rest of your understanding of Paul, I think.