Who was the strongest opposition to Paul at Corinth?
The strongest opposition to Paul at Corinth came from those who claimed to follow Peter. Right next to them were those who claimed to follow the teachings of Jesus, elevating His earthly ministry to Israel over Paul's mystery teachings for Gentiles. This opposition forced Paul to defend his apostleship.
Les explains that Paul constantly had to defend his apostleship because false teachers were coming in. The strongest element at Corinth opposing Paul and his teachings according to the mystery were those who claimed to follow Peter. Right next to that were those who claimed to follow the teachings of Jesus. Les notes this is no different today, as many say they will go by what Jesus said rather than Paul. But Les reminds that what Jesus said was to the nation of Israel under the Law, while what Paul writes is Holy Spirit inspired and directed to Gentiles in this age of grace. Paul asks if he must come with official letters from Peter and the twelve in Jerusalem, or some commendation from those who were apostles before him.