5:9 In vv. 9–11 we get some insight into the
situation Paul is addressing in chapter 5: I
wrote to you in my letter. Paul had sent a letter to the Corinthians prior
to 1 Corinthians. It seems that the Corinthians had misunderstood and/or
disagreed with Paul’s teaching in this letter on several counts, some of which
probably crop up in chapters 7–16. In response, they had written a letter back
to him (see 7:1) and he had received some reports orally. In this particular
instance Paul’s first letter should have been enough to prevent the current
fiasco of the church’s ignoring the presence of a seriously sinning member ever
occurring; Paul had already told them in his previous letter not to associate [or mix] with sexually immoral people.” (Roy
E. Ciampa and Brian S. Rosner, The First Letters to the Corinthians [The
Pillar New Testament Commentary; Grand Rapids, Mich.: Eerdmans, 2010], 216)
