The most personal thing Paul wrote, and probably not one letter. It defends his authority against rivals in Corinth, and it can be tied to an absolute date by a stone found at Delphi.
What the book is
2 Corinthians is a defence of Paul’s apostleship addressed to a community that had turned against him under the influence of rival teachers. It is the least systematic and the most emotionally exposed of his letters: it contains his account of a painful visit, a severe letter, a reconciliation, a fundraising appeal for Jerusalem, and a sustained sarcastic passage in which he lists his sufferings as credentials.
It is also the letter that tells us most about what Paul’s opponents said, because he keeps quoting them back.
How it is put together
The book does not read as a single continuous composition. The tone shifts sharply at chapter 10, from reconciliation achieved to open conflict, and chapters 8 and 9 read as two separate appeals for the same collection. Chapter 6:14 to 7:1 sits oddly in its context and uses vocabulary unusual for Paul.
The common scholarly position is that the letter is a composite, assembled from two or more genuine Pauline letters. How many and in what order is disputed. A minority defends the unity of the letter, explaining the shift at chapter 10 by an interruption or by news arriving mid-dictation.
The dating question
Paul’s letters are, with the possible exception of Haggai, the best-dated texts in the Bible, and the reason is a single external document.
Acts 18 places Paul in Corinth before the proconsul Gallio. An inscription found at Delphi, a letter of the emperor Claudius, names Gallio as proconsul of Achaia and is dated by Claudius’s imperial acclamations to around 52 CE. Since proconsuls served one-year terms beginning in early summer, Gallio’s term can be placed within a year or so.
That fixes one point in Paul’s movements, and the rest of the chronology is calculated outward from it using the intervals Paul himself gives. 2 Corinthians is written from Macedonia after Paul left Ephesus, which places it in the mid-fifties CE, commonly 55 to 57.
Where the external record touches it
The Gallio inscription is the anchor, and it deserves to be treated as what it is: a fragmentary imperial letter cut in stone, reconstructed from several pieces, that names a Roman official whom an independent narrative places in the same city as Paul. It does not mention Paul. It dates a governor, and the governor dates Paul.
Corinth itself is extensively excavated. The bema, the public platform where a proconsul would hear cases, has been identified in the forum. An inscription naming an Erastus who paid for a pavement has been connected, cautiously and not conclusively, to the Erastus named in Romans.
The manuscript evidence is early by the standards of ancient literature. The Chester Beatty papyrus P46, a codex of Pauline letters usually dated to around 200 CE, contains 2 Corinthians substantially complete.
Related: the overview of 1 Corinthians, and the method note on what external attestation means.