We have been exploring the great biblical truth of the believer’s union with Christ. We’ve seen that union with Christ defines our identity, creates a community, and produces a spirituality. There is a kind of progression involved here. We have communion with God as we are in Christ by the Spirit. Our new identity places us in a new community in the context of which we practice a new spirituality. Our purpose in this final article is to show that the end of our union with Christ does not rest on us, or even on the church. The goal of union with Christ moves from each of us toward others in the formation of Christ’s new community, the church, and on outward once again toward the world in mission as we seek to draw others into communion with God. To be united to Christ is to be sent into the world as the agents of the triune God, who gathers worshipers from the ends of the earth.

The Doxology of Union with Christ

As we think about union with Christ and mission, it will be wise to consider first the doxological purpose of union with Christ. Union with Christ is about the glory of God. This is nowhere more clearly seen than in Ephesians 1:3–14. Paul surveys the whole landscape of salvation from eternity in the electing purposes of God the Father, through history at the cross of Jesus Christ, into our experience when we believed the gospel. Each phase is explained as an aspect of the Christian’s union with Christ. We are chosen in Christ. We are redeemed by the cross in Christ. We believe into Christ. But let’s be sure to notice the goal of God in our union with Christ. What is God after in uniting sinners to His Son by the Holy Spirit? He is working that all might be “to the praise of his glorious grace” (v. 6), and that we ourselves might “be to the praise of his glory” (v. 12, 14).

What is God after when He predestines and applies to sinners their union with His Son? He is pursuing His own glory. Or, to put it another way, union with Christ is about doxology. It is about worship. It is about the exaltation of the triune Lord—Father, Son, and Holy Spirit—the one God, who is blessed forever. Ephesians 1 makes the same point Paul makes again in Romans 11:33–36. In the first ten chapters of his letter, he surveys the wonder of free salvation by grace alone through faith alone in Christ alone, the great mystery of election, and the global plan of God to bring that gospel to the ends of the earth by means of preaching the Word. After all this, it seems that Paul can’t contain himself any more. He bursts into doxology: “Oh the depths of the riches and wisdom and knowledge of God! How unsearchable are his judgments and how inscrutable his ways! ‘For who has known the mind of the Lord, or who has been his counselor?’ ‘Or who has given a gift to him that he might be repaid?’ For from him and through him and to him are all things. To him be glory forever. Amen.” What are we for? Why are we united to Christ, brought together in Him into a new community and given access to the throne of glory in authentic spirituality? What is God doing? He is working to display His glory. He is unveiling to the whole created universe the excellence of His wisdom, mercy, and grace.

And that is vital to see as we begin to think about mission because it puts the breaks on unconstrained pragmatism. There is a bigger consideration that must be brought to bear on all our efforts to serve Jesus beyond the question of whether it’s popular or attractive or whether it “works.” We need to ask, Is God being honored? Does it glorify the God who has revealed Himself in Christ by the Scriptures? Is it man-centered, or is it God-centered? The goal of union with Christ, individually and together in churches, is doxology. It is making much of God in Christ through the gospel.

The Missiology of Union with Christ

Now that we have seen the doxological purpose of God in electing, calling, converting, and sanctifying sinners, we are in a place to consider the missiological mandate of union with Christ. If the goal of union with Christ is doxology, we need to ask how that plays out. How do we achieve that goal? We began to answer that question in the previous article when we talked about spirituality. We were thinking about worship, about communing with the Trinity through the means of grace, individually and together as a church. That’s part of the answer. But another part of the answer has to do with missions.

Union with Christ compels mission. It demands it.

You may know the now famous statement with which John Piper begins Let the Nations Be Glad!, his excellent book on missions. He says: “Missions is not the ultimate goal of the church. Worship is. Mission exists because worship doesn’t.”1 We will worship forever. But we won’t do evangelism forever. We will be engaged in unceasing doxology when we come face-to-face with our exalted Savior. But there will be no more missions, no need to share the gospel. There will be no one to bring to Christ because when the new creation comes, everyone who lives there will know Him even as they are known. So, why do we engage in missions here? Because there are still men, women, boys, and girls around the world who do not know Him and do not worship Him. So, then, if the purpose of union with Christ is doxology, and the purpose of mission is doxology, there must be an intimate connection between missions and union with Christ. They both have the same goal, the same purpose.

Second Corinthians 5:14–6:1 is one place where Paul spells out the link between his missionary work and the doctrine of union with Christ. In 2 Corinthians 5:17, he reminds us that we are new creatures in union with Christ, and in 2 Corinthians 5:18–19 that we are reconciled to God because of our union with Christ. The implication of that for Paul’s own ministry is clear:

Therefore,” he says—since we are united to Christ like this in the gospel—“we are ambassadors for Christ, God making his appeal through us. We implore you on behalf of Christ, be reconciled to God. For our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God. Working together with him, then, we appeal to you not to receive the grace of God in vain (5:20–6:1).

We represent Christ, Paul explains, because we are united to Him. We speak on His behalf to the world, pleading with everyone to be reconciled to God. Indeed, we work together with Him. God Himself makes His appeal through us. That is an electrifying thought. Whether from the pulpit on a Sunday, or in a coffee shop over a muffin, when those who are united to Christ plead with the lost to be reconciled to God, God Himself makes His appeal through them. Do you see the connection between union with Christ and missions and evangelism? Because we are in Christ, Christ speaks through us, and uses us, even as we represent Him.

What are the implications of that for us? There are many, but I will mention three. First, there is boldness. Because we are in Christ and He is in us, we’re not left to our best wisdom. We don’t need to have all the answers or know all the words. We need to share the gospel simply, clearly, and lovingly, even if fearfully and tremblingly. And the power to raise the dead, and make the deaf hear, and the blind see—the saving power—lies in Christ, who will use us, despite our failings, for His glory. Fight fear with the knowledge that you are in Christ, and therefore you are His ambassador. He makes His appeal through you.

Second there is joy. Evangelism is about doxology. We are in Christ, and we get to display Christ to the world, to make much of Christ and to show the nations that life apart from Him is a dull threadbare fabric, and life in union with Him is a rich tapestry.

Third, there is vision. Mission has to be at the heart of a healthy church because the church is the community of disciples united to Jesus. Union with Christ leads to community and results in mission to the glory of God. A church is not worthy of the name if it is not working to bring men and women, boys and girls to faith in Jesus Christ and to enfold them into the life of the congregation. Union with Christ compels mission. It demands it. We betray the Savior who joined us to Himself if we keep Him to ourselves. That’s why our church’s vision is to glorify God by making disciples on the North State Street corridor, the greater Jackson area, and around the world. If we are in Christ together, we must be in Christ together for the world. To be in Christ as a church means we are a church for our neighbors and our friends and our colleagues who don’t know Jesus yet. Insularity and union with Christ are incompatible. To grow up into Him who is the Head means, in part, to go out into the world to make disciples.

Editor’s Note: This post is part of a series on union with Christ and was originally published July 7, 2019. Previous post.

  1. John Piper, Let the Nations Be Glad! The Supremacy of God in Missions (Grand Rapids, Mich.: Baker, 1993), 11. ↩︎

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