From Philippians, Colossians, Philemon, by Dennis Hamm, SJ, commenting on Colossians 3:12-17
And let the peace of Christ control your hearts, the peace into which you were also called in one body. Apart from Paul’s benediction in the prescript of the letter (1:2), this is the only other occurrence of the noun “peace” (eirēnē, as in the name Irene). But Paul surely chooses the word with awareness of his reference to Christ’s “making peace [eirēnopoiēsas] by the blood of his cross” in the climactic line of the Christ hymn (1:20).
Obviously, “the peace of Christ” is not merely the absence of war or violence but also the serenity and good order in relationships that proceeds from self-giving and self-denying love practiced in the Christian community, which participates in the self-emptying love of the Son.
And how exactly does one let the peace of Christ “control” one’s heart? The verb for “control” is another rare word, used only here in the New Testament. It carries the connotation of decisiveness. The imperative is addressed to the community as a whole, so it could be paraphrased, “Beloved brothers and sisters, let the reign of Christ’s peace be the determining factor in all your personal and community relationships.”
The image of the word of Christ dwelling in you richly draws on the cosmic poem in chapter 1. As the fullness of divinity dwells in Christ (1:19), the word of Christ dwells in the gathered worshiping community. Although one might easily hear “dwell in you” as applied to the individual, the pronoun is plural and the phrase can also be translated “among you,” and probably should be in this context.
How does this indwelling of the word of Christ come about? By way of teaching and admonition, and by singing psalms, hymns, and spiritual songs with gratitude in your hearts to God. Thus Paul gives us a fascinating interpretation of what actually goes on in liturgical song. Even as we are praising God musically, we are supporting and teaching one another by way of this shared prayer of praise.