Having delivered greetings from several other individuals and churches to the church at Corinth, Paul in the concluding verses of 1 Corinthians gives his own personal greeting to the believers in that city. He starts out by noting that he is writing the greeting in his own hand (1 Cor. 16:21). Essentially, what the Apostle means is that he is now taking up the pen and writing out 1 Corinthians 16:21–24 himself. It was common in the ancient world for letter writers to dictate their letters to a scribe or to otherwise involve a secretary in the composition of an epistle. Then, the author would write the final greeting. In the case of 1 Corinthians, Sosthenes was likely the scribe (1:1; see 2 Thess. 3:17–18).
In his final greetings, Paul includes the striking phrase, “If anyone has no love for the Lord, let him be accursed” (1 Cor. 16:22). Most likely, the Apostle here conveys one last warning for the Corinthians to make sure they heed the instruction of the letter. To put it another way, having “no love for the Lord” does not entail merely the lack of felt affection toward Christ. It also includes continuing in the kind of behavior addressed in the letter. The Corinthians erred in their factionalism based on rallying to their favorite teachers and looking down on others (chs. 1–3). It was a mistake for them to question Paul’s authority as an Apostle (chs. 4; 9). By tolerating serious impenitent sin in the congregation, suing one another over minor matters, and engaging in all sorts of sexual confusion, the Corinthians were disregarding the law of Christ (chs. 4–7). Their willingness to eat in the context of pagan worship was sinful (chs. 8; 10), as was their selfishness during the Lord’s Supper, their misuse of spiritual gifts, and their disorderly worship (chs. 11–12; 14). They went astray in denying the future bodily resurrection (ch. 15). All in all, they needed to correct this behavior by believing the doctrine and living in true love for God and for one another (ch. 13). The point of 16:22 is that if they did not correct their actions, they would prove that they did not love Christ and thus would be cut off from eternal life. Paul’s calling for the Lord to come in the same verse reminded the Corinthians that Jesus has the power to effect the curse.
Paul closes with a remark that he loves the professing believers in Corinth (v. 24). His hard words did not mean he wanted them to face destruction. He wrote as firmly as he did out of love and a desire to see their repentance.