Paul often ends his letters with such a benediction (compare 1 Cor 16.23; Gal 6.18; 1 Thes 5.28; 2 Thes 3.18). Since this whole verse is a wish or prayer of Paul for the Christians at Corinth, it may be necessary in the receptor language to introduce it by saying “It is my desire that…” or “I pray that…” (Contemporary English Version).
On The grace of the Lord Jesus Christ, see comments on 8.9, and compare 1 Cor 1.3. Grace must not be understood as a quality or characteristic of Christ but as something which he does. In some languages it will be more natural to say something like “I pray that the Lord Jesus Christ will show his kindness to you….”
Since the first part of this verse must mean the grace that comes from Jesus Christ, the other two parts of the verse probably mean the love that God has for them (“May God bless you with his love,” Contemporary English Version) and the fellowship that the Holy Spirit creates (“May the Holy Spirit join all your hearts together,” Contemporary English Version). It is possible, however, but not as likely, that Paul refers to love for God and fellowship with the Holy Spirit.
You all: as in Rom 15.33 and 1 Cor 16.24, the second person plural pronoun is accompanied by the inclusive adjective all, thus highlighting the extent of Paul’s wish for the Corinthians. This comprehensiveness is also emphasized several times earlier in this letter (2.3, 5 and 7.13, 15).
The following model may be helpful in some languages: “I pray for all of you that the Lord Jesus Christ will continue to be gracious to you, that God will continue to love you, and that the Holy Spirit will unite you in his fellowship.”
Some manuscripts add the word “Amen” to the end of this letter (see King James Version, Reina-Valera revisada), but scholars today agree that this word was later added by a scribe and was not written by Paul. It should therefore not be used in the receptor language.
Quoted with permission from Omanson, Roger L. and Ellingworth, Paul. A Handbook on Paul’s Second Letter to the Corinthians. (UBS Handbook Series). New York: UBS, 1993. For this and other handbooks for translators see here .