2 Corinthians 3

God declares righteous those who believe in His Son. We are justified by Christ and sanctified by the Holy Spirit. Christ died for us and took upon himself our sin so that we can stand before God in Christ. The Holy Spirit changes us, precept upon precept, into the image of His Son Jesus Christ. We become living epistles of God's agape love, mercy and grace.

3 Do we begin again to commend ourselves? Or do we need, as some others, epistles of commendation to you or letters of commendation from you? 2 You are our epistle written in our hearts, known and read by all men; 3 clearly you are an epistle of Christ, ministered by us, written not with ink but by the Spirit of the living God, not on tablets of stone but on tablets of flesh, that is, of the heart.

4 And we have such trust through Christ toward God. 5 Not that we are sufficient of ourselves to think of anything as being from ourselves, but our sufficiency is from God, 6 who also made us sufficient as ministers of the new covenant, not of the letter but of the Spirit; for the letter kills, but the Spirit gives life.

12 Therefore, since we have such hope, we use great boldness of speech— 13 unlike Moses, who put a veil over his face so that the children of Israel could not look steadily at the end of what was passing away. 14 But their minds were blinded. For until this day the same veil remains unlifted in the reading of the Old Testament, because the veil is taken away in Christ. 15 But even to this day, when Moses is read, a veil lies on their heart. 16 Nevertheless when one turns to the Lord, the veil is taken away. 17 Now the Lord is the Spirit; and where the Spirit of the Lord is, there is liberty. 18 But we all, with unveiled face, beholding as in a mirror the glory of the Lord, are being transformed into the same image from glory to glory, just as by the Spirit of the Lord.

The
NKJV
says this:

Paul asked if he needed a letter of commendation to back him up, as some others did. The Corinthians were Paul's letter of recommendation. Paul's love for the Corinthians was known to all who were acquainted with his ministry. One of the qualifications for ministry is love for people, both God's people and the lost. God had changed them. Paul was convinced that Christ would make his ministry effective. Paul placed his confidence not in himself or his own abilities but in the Lord. The letter kills because all break the law, and the penalty is death. The ministry of the Law is the ministry of death, whereas the ministry of the Spirit is the ministry of life. The Holy Spirit produces eternal life. God declares righteous
those who believe in His Son, and then the Holy Spirit empowers the believer to live righteously. This first work of God is called justification, and the second is called sanctification. Whenever Moses turned to the Lord, he took off the veil. Likewise, we find freedom in Christ by looking to Him. The Spirit gives us freedom from sin, death, and the condemnation of the law. The Holy Spirit is God Himself, like the Father and like the Son. As believers behold the glory of God in the Word of God, the Spirit of God transforms them into the likeness of Jesus Christ. This is a description of the gradual process of sanctification. Paul defended his ministry because it was based on the truthfulness of the Word of God.