The doctrine of union with Christ is central to understanding the riches of God's grace in the gospel and all of its implications. Whether it be from the words of Jesus Himself, particularly in passages such as John 15, or from the Epistles saturated with phrases such as "in Him," "through Him," and "by Him," it is evident that union with Christ is essential for both defining what Christians are and what we possess. Moreover, this union has tremendous implications within the context of Christian fellowship.
We are familiar with the biblical language that likens the corporate body of believers to a single human body (Rom. 12:4–5; 1 Cor. 12:12–27; Eph. 4:15–16). The basis for such metaphors is the faith of individual Christians in a common body of truth, that is, the gospel. The Apostle John expresses it this way: "That which we have seen and heard we proclaim also to you, so that you too may have fellowship with us; and indeed our fellowship is with the Father and with his Son Jesus Christ" (1 John 1:3; see also 1 Cor. 15:1–2). Or, consider the Apostle Paul's words in 1 Corinthians 1:2: "To the church of God that is in Corinth, to those sanctified in Christ Jesus, called to be saints together with all those who in every place call upon the name of our Lord Jesus Christ, both their Lord and ours." As important as our secondary doctrines are (those that determine our denominational affiliations and local church choices), what unites us as Christians is our faith in what Jude calls "our common salvation" and "the faith that was once for all delivered to the saints" (v. 3).
At the risk of sounding like a minimalist or reductionist, our union with Christ ought to cause us to be collegial and gracious in our disputes, debates, and dialogues with others who also "call upon the name of our Lord Jesus Christ," but with whom we may have significant differences on various points. Our consciences and respective confessions may not allow us to worship together or even cooperate in different endeavors, but our mindset should be that those who look by faith to the person and work of Jesus Christ for their salvation are, as far as we are able to tell (as no one knows the heart of another), brothers and sisters in the faith.
In Ephesians 1:15 and Colossians 1:4, Paul commends his readers for their "love for all the saints." We would do well to foster such a spirit. We should not treat professing Christians in our families, on our jobs, and in our neighborhoods as if they had a contagious disease when we have minor doctrinal differences with them. Rather, we should see them as those for whom Christ died. We should not be ready to attack on those points of disagreement but to seek gracious ways to show them a more excellent way. If meekness and humility are to characterize how we defend the faith before unbelievers (1 Peter 3:15), how much more should we strive for this spirit in our dealings with other Christians?
In addition to motivating us to deal with other Christians with civility and love, our union with Christ ought also to govern how we view Christians throughout the world that we may never see face to face in this life. Apart from denominational mission support or the occasional visit from an actual foreign missionary to a local church in an effort to gain support, most American Christians are simply unaware of what other Christians endure and suffer because of their faith. In no way do I mean this as an indictment. It is simply a reminder that union with Christ and the communion of the saints ought to enlarge our vision of the body of Christ and the diverse circumstances and situations that many of our brothers and sisters face. I'm sure that most of us share in financial support for missionaries and mission work. American Christians have proven to be very generous in providing relief and aid when disaster strikes in any part of the world. But as we wrap our minds around the concept of our union with Christ and the communion of the saints, I pray that we would make room in our personal and corporate prayers for brothers and sisters in any number of situations.
A number of years ago, I was conducting interviews at a major Christian event and was approached by a brother who asked me to interview a gentleman that he was supporting from a sub-Saharan African country. As it turned out, the gentleman that I was being asked to interview was an African pastor who had devoted his life to purchasing the freedom of Christians who had been taken by Muslims as prisoners of war and sold as slaves. We should think about underground churches in different countries, as well as inmates and those who minister to inmates here or abroad. Union with Christ and the communion of the saints should cause us to see that the struggles of these Christians are our struggles as well.
Let us not be so consumed with what is happening in our part of the vineyard that we do not see the glory of Christ in the lives and issues of brothers and sisters purchased by the same blood, who uphold the same faith. "Let no one boast in men. For all things are yours, whether Paul or Apollos or Cephas or the world or life or death or the present or the future—all are yours, and you are Christ's, and Christ is God's" (1 Cor. 3:21–23).