The books of the Bible that we know as 1 & 2 Corinthians were probably the second and either the third or fourth letters he wrote to the church in Corinth. We can piece this together fairly easily from what we do have even if we don’t have an exhaustive collection of all Paul’s letters.

As recorded in Acts 18, Paul visits Corinth for the first time on his second missionary journey and spends a year and half there. About a year or two later he spends two years in Ephesus (Acts 19:10) on his third missionary journey and likely writes what we know as 1 Corinthians during this time. In 1 Corinthians 16:8, he writes “I will stay in Ephesus until Pentecost.” And we know that 1 Corinthians was not the first letter he wrote to the church in Corinth because in 1 Corinthians 5:9, Paul writes “I wrote to you in my letter…”

Then there’s a third letter which we don’t have which Paul describes in 2 Corinthians 2 sometimes known as the “severe” letter. It is generally believed to be different than what we know as 1 Corinthians because the way Paul describes its tone doesn’t seem to match 1 Corinthians. Therefore, what we know as 2 Corinthians may very well be 4th Corinthians.