Problem: Paul refers to a previous epistle he “wrote” to the Corinthians which is not in existence. But since it was written by an apostle to a church and contained spiritual and authoritative instruction, it must be considered inspired. This raises the question as to how an epistle inspired of God could be allowed by Him to be lost.
Solution: There are three possibilities here. First, it may be that not all apostolic letters were intended to be in the canon of Scripture. Luke refers to “many” other gospels (1:1). John implies that there was much more Jesus did that was not recorded (20:30; 21:25). Perhaps this so-called “lost” letter to the Corinthians was not intended by God to be collected in the canon and preserved for the faith and practice of future generations, as were the 27 books of the NT (and 39 of the OT).
Second, others believe that the letter referred to (in 1 Cor. 5:9) may not be lost at all, but is part of an existing book in the Bible. For example, it could be part of what we know as 2 Corinthians (chaps. 10–13), which some believe was later put together with chapters 1–9. In support of this is offered the fact that chapters 1–9 have a decidedly different tone from the rest of the Book of 2 Corinthians (chapters 10–13). This may indicate that it was written on a different occasion. In addition, they point to the use of the word “now” (in 5:11) in contrast to an implied “then” when the former book was written. They also note that Paul refers to “letters” (plural) he had written in 2 Corinthians 10:10.
Third, others believe that Paul is referring to the present Book of 1 Corinthians in 1 Corinthians 5:9, that is, to the very book which he was writing at the time. In support of this they note the following:1) Even though the Greek aorist tense used here (“I wrote”) may refer to a past letter, it could also refer to the book at hand. This is called an “epistolary aorist,” because it refers to the very book in which it is being used.2) In Greek, the aorist tense is not a past tense as such. It has reference to the kind of action, rather than to the time of action. It identifies a completed action that may have even taken a long time to be accomplished (cf. John 2:20).3) The aorist tense often implies a decisive action, in which case Paul would be saying something like this: “I am now decisively writing to you.” This certainly fits the context of this passage in which he is urging the church to take immediate action to excommunicate a wayward member.4) An “epistolary aorist” is used by Paul elsewhere in this very letter when he said, “I am not writing these things that it may be done so in my case” (1 Cor. 9:15, nasb).5) There is absolutely no indication in early church history that any such letter of Paul, other than the existing 1 and 2 Corinthians, ever existed. The reference in 2 Corinthians 10:10 saying, “his letters are weighty” may mean no more than “what he writes is weighty.” And the “now” of 1 Corinthians 5:11 need not indicate a later letter. It can be translated “rather” (rsv) or “actually” (nasb).
“I wrote unto you in an epistle not to company with fornicators: (1 Cor 5:9)”