What does 2 Corinthians 10:3 mean?

Some in Corinth have said Paul is brave when writing letters far away but unconfident and timid when he is with them in person. The false teachers or false apostles who had come in among the Corinthians may have been more naturally impressive in person. In verse 10, Paul will quote these opponents as saying about him, "His letters are weighty and strong, but his bodily presence is weak, and his speech of no account." In the prior verse, Paul warned them not to mistake his Christlike meekness—which refers to strength under control—for weakness.

He says that though he and his friends walk in the flesh, he is not waging war according to the flesh. In saying this, Paul seems to be using a different meaning than we usually associate with this phrase, perhaps intentionally turning it around from the previous verse to make his point. Instead of meaning living in a "fleshly" way, driven by the body's sinful desires, Paul changes the phrase to mean living only according to the limited abilities of a human body. In this letter, he has already described his own limited body as wasting away (2 Corinthians 4:16). In other words, Paul does not see himself as physically strong or impressive.

In that sense, Paul writes, his opponents are right. He is limited by his "flesh," his body. He adds, though, a bit ominously, that he does not wage war according to the flesh. As he will clarify in the following verses, he and his co-workers see themselves as engaged in spiritual warfare, doing battle with spiritual weapons. In saying this, he is making clear to the Corinthians that he sees this disagreement with his opponents in Corinth as more than a mere political struggle over authority. It is nothing less than a spiritual war with eternal consequences.