CLAIM: Paul writes, “Now I rejoice in what was suffered for you, and I fill up in my flesh what is still lacking in regard to Christ’s afflictions, for the sake of his body, which is the church” (Col. 1:24). Do believers need to finish the work of Christ on Earth?
RESPONSE: A number of responses are in order:
First, the rest of the NT states that Christ’s work was complete. Jesus purchased our salvation “once for all” (Heb. 9:12; 10:10; 1 Pet. 3:18). Jesus said that he had “accomplished the work which [God] have given [Him] to do” (Jn. 17:4). After he had paid for human sin, Jesus himself said, “It is finished” (Jn. 19:30). The author of Hebrews writes, “He, having offered one sacrifice for sins for all time, sat down at the right hand of God… For by one offering He has perfected for all time those who are sanctified” (Heb. 10:12, 14). Earlier, Paul wrote that Jesus already “reconciled you in His fleshly body through death” (Col. 1:22). Later, he writes, “In Him you have been made complete” (Col. 2:10). We would be gravely mistaken to think that Christ needs the Church to pay for human sin.
Second, the term “afflictions” (thlipseōn) is never used of Jesus’ work on the Cross. This is confirmed by various commentators including Wright, Patzia, and Vaughn. Therefore, it’s unlikely that Paul has Jesus’ work on the Cross in mind, when he speaks of Christ’s sufferings here.
Third, Paul is thinking of our mystical union with Christ. Jesus suffered once and for all for us in purchasing our salvation, but he continues to suffer through us to spread the message of his salvation. When Jesus confronted Saul on the Damascus Road, he asked, “Saul, Saul, why are you persecuting Me? …I am Jesus whom you are persecuting” (Acts 9:4-5). Since believers are part of Christ’s body (1 Cor. 12:13), he identifies our suffering with his own. Elsewhere, Paul writes, “The sufferings of Christ are ours in abundance” (2 Cor. 1:5), and we have “the fellowship of His sufferings” (Phil. 3:10).
Conclusion. Jesus’ work was complete on the Cross, but since he continues to identify with his Church, he continues to suffer with us until he returns.
 N. T. Wright, Colossians and Philemon: An Introduction and Commentary, vol. 12, Tyndale New Testament Commentaries (Downers Grove, IL: InterVarsity Press, 1986), 93.
 Arthur G. Patzia, Ephesians, Colossians, Philemon, Understanding the Bible Commentary Series (Grand Rapids, MI: Baker Books, 2011), 40.
 Curtis Vaughan, “Colossians,” in The Expositor’s Bible Commentary: Ephesians through Philemon, ed. Frank E. Gaebelein, vol. 11 (Grand Rapids, MI: Zondervan Publishing House, 1981), 190.