The Galatian believers fell from grace because they went back to the law for their justification (5:4). They wanted to be justified by their keeping of the law. By doing this, they fell away from the grace.
Galatians 6:18 says, “The grace of our Lord Jesus Christ be with your spirit, brothers. Amen.” Paul closed the book of Galatians in this way because the Galatians forgot about the indwelling Spirit. The grace of the Lord Jesus Christ is the bountiful supply of the Triune God (who is embodied in the Son and realized as the life-giving Spirit) enjoyed by us through the exercise of our human spirit. Paul, in his conclusion, reminded the believers in Galatia that the grace of the Lord Jesus Christ was in their spirit. Grace is not objective but very subjective. Grace is in our spirit for our remaining in God’s New Testament economy. If we fall away from grace, we have nothing to do with God’s New Testament economy. Grace nearly equals the New Testament economy of God, just as the law nearly equals the Old Testament economy of God.
Ephesians 1:6 and 7 speak of the rich grace of God with which God graced us, the believers, in three main things: in choosing us, predestinating us, and redeeming us. Of course, these three things issued in a big result. God’s choosing, predestinating, and His redeeming in Christ produced the Body of Christ (vv. 22-23). These three things are in the first part of the first chapter of Ephesians. But from the second part of the first chapter of Ephesians to the last chapter, the big issue of these three items is the Body of Christ.
Ephesians 2:5-8 speaks of the grace by which the believers have been saved through the death and resurrection of Christ and of which the surpassing riches might be displayed in the ages to come. This rich grace will be for the display, the exhibition, in eternity. In other words, the New Jerusalem will be a big show, a big exhibition, to display the rich grace of God, which has done everything to produce the New Jerusalem.
Paul was given the stewardship of the grace of God to carry out God’s New Testament economy in Christ (Eph. 3:2, 7-9). The stewardship is the service of a steward, who is a family servant. With Paul the stewardship from God became very great. The stewardship of the grace is for the dispensing of the grace of God to His chosen people for the producing and building up of the church. The grace came upon the apostle Paul, making Paul one who knew that God does everything to replace man. Even though Paul labored more than all the apostles, he said that it was not him but the grace. This was his stewardship for the accomplishment of the economy of God in Christ.