ISB ~ 2 Corinthians 3 v1

letters of recommendation:Written referrals were sometimes sent ahead of traveling missionaries to prepare for their arrival in a new Church (Acts 18:27; Rom 16:1; 1 Cor 16:3). Apparently Paul’s opponents furnished such resumes for themselves and misled the Corinthians into thinking they were genuine apostles (2 Cor 10:12). In contrast, Paul does not need to reestablish rapport in Corinth by written statements (5:12) but can point to the Church’s conversion as proof that his ministry is authentic (Acts 18:1-18).