Philemon

Thirteen letters from one apostle, read by the occasions that drew them out of him — the church-planting follow-ups, the prison letters, and the pastorals.

The gospel's most private, costly work in one household: Paul appeals rather than commands for a runaway slave, offering to personally absorb his debt — 'put that on mine account.'

The reckoning-word across the canon: Abraham believed and it was reckoned (Gen 15:6), David's blessedness (Ps 32), Romans 4's counted-for-righteousness, the exchange of 2 Cor 5:21, and Philemon 18's 'put that to mine account.'

The historical frame, what the Law actually protects, Paul's letter to a slave-owner, and the objection presented at full strength, unsoftened — a contested topic handled honestly, no triumphalism.