1. Weapons of warfare (10:1-6). This section begins a rather unfortunate tone that Paul felt compelled to adopt. It was unfortunate only in that some Christians in Corinth adopted an attitude that needed to be checked. Paul took no pleasure in this, but he did tend to it as he felt it was required. How do we tend to such unpleasant tasks like those to whom Paul addressed this portion of his epistle? We should do as Paul did; Paul did not war according to the flesh (10:3).
2. Outward appearances (10:7-11). It is so easy to write harder than it is to present oneself in a similar way. Some may not have much difficulty, but most do. It was said about Paul that he was one way in print and another way in presence, and perhaps he was; there is nothing wrong with this, but Paul was only this way when conditions demanded it. When one writes correspondence it is likely that much is missing that would help the tone of a letter be better adjusted. Paul received word from Chloe and perhaps some others (1 Corinthians 1:11), but without him being present a whole picture can only be interpreted in part. However, when present, Paul (and others) can get a better read and adjust the tone of the voice, the content of the message, and the same with a follow-up letter.
3. Comparison (10:12-18). Though Paul might have had limited information, he had enough information to write this epistle and write a scolding word toward those who were doing so much comparing. Comparing oneself to another is, truly, a fruitless act. What good can come from it? If you think that some good can come from it, will you continue to the point of looking at yourself in a better light than otherwise (cf. 1 Corinthians 4:6). If you insist on making a comparison, compare with one who will keep you humble – the Lord Jesus.