1 Corinthians 9:2, Seal of Apostleship
The Apostle Paul reasoned with the church in Corinth that he was sent by Jesus Christ to preach the gospel to them. The fact that they are in the Lord attest his apostleship. God’s grace came upon them to open their hearts and to save them. Why did he have to speak thus? Because the believers in Corinth were resisting to amend their ways according to the counsel that the Apostle Paul was giving to them. Instead, they have chosen to undermine his authority by raising in question his God-given mandate, for their spiritual welfare.