13:11 Obedience to five commands would result in one condition that Paul wanted his readers to express in a particular practice.
1. They were to rejoice, probably because they had the opportunity to judge themselves before God would judge them (cf. 1 Cor. 11:31). What is more important they could and should rejoice in the Lord.
2. They were to mend their ways (RSV) and thus experience completion or restoration as God would bring them to maturity (cf. v. 9). They needed to break permanently with all idolatry (6:14-7:1), to complete their collection (chs. 8-9), and to change their attitude toward Paul (chs. 10-13).
3. They were to accept Paul's exhortation that would result in their comfort (cf. 1:3-10).
4. They were to foster a united outlook by putting first things first (cf. v. 8). Specifically they needed to unite in their attitude to Paul and his authority.
5. They were to live at peace with one another and with Paul.
These conditions being met the God who manifests love and peace as the fruit of His Spirit would remain in fellowship with them. They should emulate God and cultivate love and peace toward one another and toward the apostle.
"It is not by sitting with folded hands that we enter into the blessings of God, but by actively and purposefully promoting those dispositions which are in accordance with God's will for His people: rejoicing, harmony, unity in the truth, living together in peace. It is true that we look to God alone to supply the grace for their achievement; but it is the actual daily practice of love and peace that ensures, from the human side, the realization of the promise that the God of love and peace will be with us."294
13:12 They could then exchange the holy kiss sincerely. The believers practiced this custom commonly. It symbolized the forgiveness, reconciliation, unity, and fellowship that existed between the people who kissed each other. Until unity prevailed in the church this kiss was hypocritical.
(NT only) to listen to the NET Bible 
