My Final Answer:
The “lack” that Paul’s sufferings are filling up is the representative absence of Christ’s redemptive sufferings. Let me expound: What Christ did on the cross was a singular event in space and time, yet it was for all time and for all people. The distance between the singular event and the fullness of humanity is the lack. The application of reconciliation needs to be extended to all people. That is where Paul’s suffering, and your suffering and my suffering come in. We suffer to fill up the lack of proclamation of Christ’s propitiation. Therefore, what Christ propitiated, we proclaim. What he did, we declare. The redemption he accomplished we make known through declaration, and as the Lord ordains our sufferings for his sake, we demonstrate his death and resurrection in our bodily afflictions.
Commenting on this, John Piper writes:
Christ has prepared a love offering for the world by suffering and dying for sinners. It is full and lacking nothing—except one thing, a personal presentation by Christ himself to the nations of the world. God’s answer to this lack is to call the people of Christ (people like Paul) to make a personal presentation of the afflictions of Christ to the world…In [our] sufferings they see Christ’s sufferings. Here is the astounding upshot: God intends for the afflictions of Christ to be presented to the world through the afflictions of his people (Desiring God, 225).
In short, Paul’s suffering validated and attested to the life-giving power of the message he proclaimed, so that in his life he demonstrated Christ’s sacrificial death and resurrection power (cf. Phil. 3:9-10). In the church, the world is able to see the body of Christ. In the suffering of Christ’s body, they are given a living, breathing, suffering testimony of the savior who bled and died to make reconciliation with God possible. This was God’s design for his church from the beginning. Reflecting on this call to suffer, Romanian pastor Joseph Tson comments:
[Speaking in first person, in the life of Paul, he says]: If I had remained in Antioch…nobody in Asia Minor or Europe would have been saved. In order for them to be saved, I have had t accept being beaten with rods, scourged, stoned, treated as the scum of the earth, becoming a walking death. But when I walk like this, wounded and bleeding, people see the love of God, people hear the message of the cross, and they are saved. If we stay in the safety of our affluent churches and we do not accept the cross, others may not be saved. How many are not saved because we don’t accept the cross? (Quoted by John Piper in Desiring God, 230).
Let me summarize: Christ’s sufferings redeemed; Paul’s sufferings reveal. They do not add to Christ’s all-sufficient work, but they do extend its all-sufficient power and message (cf. 2 Cor. 4:7-11). The purpose of God in Christ’s sufferings was to redeemed a people dead in trespasses and sins; the purpose of God in Paul’s sufferings was to bear witness to the sufferings of another, and amazingly Paul’s bodily afflictions were designed by God to advance that message. So then, Paul’s sufferings for the gospel, and ours, are not supplementary, but complementary. They are essential, not optional.
Jesus promised his followers a cross. He said that if the world hated the master, they would also hate his servants. Therefore, in telling the world about his saving work, we can expect to suffer. Yet, in that suffering we demonstrate in our flesh the power of God’s love and the very cross that we declare. When the world sees suffering, bleeding, dying Christians telling of their suffering, bleeding, dying savior with joy (“I rejoice in my sufferings for your sake,” Col. 1:24a), they are filling up what is lacking in Christ’s afflictions—namely the representative witness of the savior’s redemption. And in so doing, we follow in the faithful footsteps of Paul and we fill up what is lacking in Christ’s afflictions.
Lord Jesus, give us more grace to move towards the suffering you have designed for us to embrace in our bodies, and may the world know that while we suffer, we do it joyfully, looking forward to the resurrection of the body in the age to come.
Sola Deo Gloria, dss