3:3 letter from Christ delivered by us. The Corinthian church was a work of God’s grace, but in this work Paul and his co-workers had been God’s instruments.

tablets of stone. The Ten Commandments.

tablets of human hearts. Paul’s point is twofold. First, the “letter,” which the Corinthians are, is superior to the pen-and-ink letters of his opponents as well as the stone tablets of the law. Second, Paul presents the fruits of his apostleship as the fulfillment of Old Testament prophecy. As predicted in Jer. 31:33 and Ezek. 11:19; 36:26, in the new covenant God writes His laws on the hearts of His people, giving them a new desire and ability to obey Him. The law that is written in the heart is the unchanging and pure law of God, that is, His absolute moral standard.