Previous ruminations on Colossians 1 have taken us through exercising faith while in Christ, believing as doing, Christ the image of God, and the need to participate in Jesus’ saving death through faith.
Jesus’ death reconciles all things. Which makes Paul’s statement at the end of the chapter all the more surprising:
Now I’m happy to be suffering for you. I’m completing what is missing from Christ’s sufferings with my body. I’m doing this for the sake of his body, which is the church. (Col 1:24, CEB)
Paul sees himself so intimately tied to God’s work of redeeming the world in Christ that his own sufferings are wrapped up into the saving death of Jesus. Later in this paragraph, he will say that he is completing the mystery of God by including the Gentiles in the people of God (Col 1:26). And in ch. 2 he will say that Christ himself is the mystery.
All of these pieces work together.
Christ is the mystery. His body is the global body of a reconciled humanity at one with God and purified in himself. The means by which this global mystery comes to revelation is Jesus’ own death and the subsequent ministry of Paul (and others).
Ministers are extensions of the saving work of Christ on the cross. The body of believers is an extension of the saving work of Christ on the cross. In the already/not yet eschatology of a world reconciled and being reconciled to God, the death of Jesus is both a one-off reconciling event and a saving reality that the church is called to extend in space and time.
Paul sees suffering as necessary because he sees a world that is not yet fully subject to the reigning Christ. The means of Christ’s attainment of glory must therefore be perpetuated among Christ’s ambassadors who are bringing that work to its culmination and fulfillment.
So long as there are people who do not know the message, so long as there are ministers taking it to new places, there will be people filling up what is lacking in Christ’s afflictions.