What does 1 Corinthians 15:9 mean?

Paul is not expressing self-pity or even self-hatred in this verse. He has described himself among the other apostles as one "untimely" or "abnormally" born. Unlike the men who were selected and trained by Jesus during the Lord's time on earth, Paul was confronted and converted by Christ after Jesus has already returned to heaven (Acts 9:3–6; 22:6–11).

It's not because of Paul's lateness to faith in Christ, though, that he describes himself as unworthy of the title "apostle." It's because he actively opposed Christ and those who followed him. As a high-ranking Jewish Pharisee, Paul applied all his energy and strategy to wiping out Christianity in its earliest form. To accomplish this, he hurt, imprisoned, and even killed Jewish people who had converted to faith in Christ. Here's how he described this season of his life in Acts 22:4, "I persecuted this Way to the death, binding and delivering to prison both men and women."

Paul acknowledges that, in human terms, such actions should have disqualified him from ever representing Christ as an apostle. That's not how God works, though, as Paul shows in the following verses.