Practical Grace
You may wonder why the Lord Jesus called Paul to be an apostle. Paul wondered too! He knew that he did not deserve God's favour because he had persecuted the church (which was the same as persecuting Jesus Christ Himself - Acts 9:4). His only answer was that God called him by His grace. It was unmerited, unwanted, unexpected; a free gift from God's heart of love. The Lord called Paul because He chose him (Deuteronomy 7:7). It was God's sovereign choice. Paul knew he was under divine command and he obeyed (Acts 9:5-8, 15-16).
Paul had no pride in his salvation, only shame that he had resisted the Lord Jesus for so long, and had injured the church. Neither would he take any credit for the remarkable change in his character, and life-purpose; that too was the powerful influence of God's grace. He became what God made Him – forgiven, filled with the Spirit, gifted to evangelise and teach, willing to suffer hardship – all through the grace of God. Paul's life had changed because the Lord changed his heart, desires, motives and ambitions.
That grace had not only motivated but also empowered Paul to work very hard and suffer cheerfully. The apostle allowed God's grace to operate in his life, to change his thinking and to energise his service. The Lord did it, and the apostle did not resist the mighty hand of God. Humbly, it did not matter to Paul who had preached the gospel to people in Corinth: the message was more important than the messenger. The message was that Jesus who died for their sins was raised in a new physical body to show that they were right with God; and that Jesus who was despised became exalted and could give His gifts of grace to whoever He chose.
Pride has no place in the church. Yes, the Lord calls us and enables us to work very hard; but it is all through His grace. It is not what we do (Ephesians 2:8-9). Yes we must explain the gospel to people and urge them to repent and receive Christ, but it is the Lord who stirs in their soul, convicts them of sin and brings willing penitents to salvation. Of ourselves we are nothing; if the Lord enables us, we are still nothing so that He will get the glory. We are the messengers, the servants and the stewards of the gospel of grace (Acts 20:24). The Corinthian church had forgotten that; have you?