Problem: The Bible declares that Jesus’ death on the cross was both sufficient and final for our salvation (John 19:30; Heb. 1:3). Yet Paul states that we are to fill up what is “lacking in the afflictions of Christ.” But if the Cross is all-sufficient, then how can anything be lacking in Christ’s suffering for us?
Solution: Christ’s death on the Cross is sufficient for our salvation. The Bible makes this emphatically clear. Anticipating the Cross, Jesus said to His Father, “I have finished the work which You have given Me to do” (John 17:4). On the cross He cried out, “It is finished!” (John 19:30). The Book of Hebrews declares unequivocally that “by one offering [on the cross] He has perfected forever those who are being sanctified” (Heb. 10:14). And this He did “by Himself” (Heb. 1:3), with no help from anyone else.
Nevertheless, there is a sense in which Christ still suffers after His death. Jesus said to Paul, “Why are you persecuting Me?” In this sense, we too can suffer for Him, since “it has been granted on behalf of Christ, not only to believe on Him, but also to suffer for His sake” (Phil. 1:29). But in no sense is our suffering for Christ a means of atoning for sin. Only Jesus suffered for sin. We suffer because of sin (ours and others), but never for sin. Each person must bear the guilt of his own sin (Ezek. 18:20) and accept the fact that Christ suffered for his sin (1 Peter 2:21; 3:18; 2 Cor. 5:21). When we suffer for Christ, we are undergoing pain as part of His spiritual body, the church, but only what Christ suffered in His physical body on the Cross is efficacious for our sins. Our suffering, then, is in service, not for salvation.
“Who now rejoice in my sufferings for you, and fill up that which is behind of the afflictions of Christ in my flesh for his body’s sake, which is the church: (Col 1:24)