We see that the legalists who caused trouble in both Antioch and Jerusalem had come to Corinth and enticed some of the believers into living by the Law of Moses. Paul refuted their position by showing the wonders of the new covenant ministry. The background is Exodus, chapter 34. It changes hearts, this new covenant.
The law only reveals sin. It cannot renew the inner person. The Spirit wants to write a new version of his word on your heart, will you let him? Warren Wiersbe in his great Bible Commentary, Chapter by Chapter Bible Commentary says it gives life, the Law kills, but grace gives life and sustains that life. God’s children have a living relationship with him through the spirit of life. Oh, and by the way, it gets more and more glorious. The glory of the Law is gone. The temple, the priesthood, the ceremonies, and the awesome revelations of God’s power, it’s all gone.
But the glory of God’s grace remains and grows more and more glorious and brings freedom. The Law brings bondage, but grace gives glorious freedom. That makes us more and more like Jesus Christ each day. You can have your own personal transfiguration as you worship the Lord and yield to the Spirit.
Not that we are sufficient in ourselves to claim anything as coming from us, but our sufficiency is from God, who has made us sufficient to be ministers of a new covenant, not of the letter but of the Spirit. For the letter kills, but the Spirit gives life. ~ 2 Corinthians 3:5-6