A lot of Christians have been confused about that issue. So let’s look at what Paul wrote. He stated in Galatians 4:13, “You know how through infirmity of the flesh I preached the gospel unto you at the first.” The two phrases we need to fully understand are “infirmity of the flesh” and “at the first.”
Something that happened soon after Paul’s conversion sheds some light on this. At the time, God said to Ananias, “I will show him (Paul) how great things he must suffer for my name’s sake,” referring to persecutions. Writing about this, Paul states, “Therefore, I take pleasure in infirmities, in reproaches, in necessities, in persecutions, in distress for Christ’s sake: for when I am weak, then am I strong” (2 Corinthians 12:10).
What Paul was acknowledging was his weakness and inability in his own strength to stand up against the strategies of the devil. That is why he said, “For when I am weak then am I strong.” He recognized that God’s grace was more than enough. So in Galatians 4:13, the word “infirmity” means weakness of the flesh, not sickness or disease.