Philip Schaff, the distinguished nineteenth-century church historian, calls the saying in our title “the watchword of Christian peacemakers” (History of the Christian Church, vol. 7, p. 650). Often attributed to great theologians such as Augustine, it comes from an otherwise undistinguished German Lutheran theologian of the early seventeenth century, Rupertus Meldenius. The phrase occurs in a tract on Christian unity written (circa 1627) during the Thirty Years War (1618–1648), a bloody time in European history in which religious tensions played a significant role. The saying has found great favor among subsequent writers such as Richard Baxter, and has since been adopted as a motto by the Moravian Church of North America and the Evangelical Presbyterian Church. Might it serve us well as a motto for every church and for every denomination today?
Those who are united by faith in Christ are thereby united to one another in the church, the body of Christ. We call this union the communion of saints. It is a mysterious thing, and to understand it properly we will need to see it both in its “now” and “not yet” aspects. Because it is a union created by Christ in baptizing us all by one Spirit into His body, the church (1 Cor. 12:12–13), it is true of all Christians now, a fait accompli. But the manifestation of that unity is not always apparent. Christians can display ugly divisions between one another, as at the church of Corinth (1:10–17). Their disunity could be seen in the public square as members sued one another before the ungodly in civic courts (6:1–8). Even the Lord’s Supper was not sufficient to bring them together in love and unity (11:17–34). Manifesting fully the unity in Christ that already is given to us belongs to the “not yet” perfection of the faith that will come at our glorification. With deep longing our Lord prayed for our unity, knowing that on it rests our own blessing and the credibility of the church’s witness for Christ (John 17:20–23).
Tensions arising from diversity of belief and practice among Christians are already apparent in the pages of the New Testament and remain with us today. There was apparently a thriving vegetarian faction within the church at Rome (Rom. 14). “One person believes he may eat anything, while the weak person eats only vegetables” (v. 2). There was also a difference among them about whether certain days were to be honored (v. 5). How do we live with such differences among us? Paul says, “As for the one who is weak in faith, welcome him, but not to quarrel over opinions” (v. 1). Such a person is to be welcomed, says Paul, and not just welcomed for the purpose of quarreling with him over his views. Love for such a person, weak in faith though he is, must continue.
In that love, we must extend liberty to each person to hold fast to his own conscience on what Christ has commanded (Rom. 14:5); but how far can that liberty be extended? Apparently, it would extend far enough to include vegetarians and those who maintained that Christians should continue to honor the Jewish feast days. But would it also include Baptists receiving into church membership people with paedobaptist convictions, or paedobaptists receiving members with Baptist convictions? Should believers who hold to a corporeal presence of Christ in the Lord’s Supper admit to the table those who believe the real presence of Christ in the Supper is spiritual and not corporeal? After two thousand years of church history, Christians are still divided on many key doctrinal issues, even on the very signs of our unity in Christ—baptism and the Lord’s Supper. How, then, can we be one in Christ and demonstrate the communion of saints? It would seem that either we must ignore our doctrinal differences and treat them as inconsequential, or we must remain permanently divided and in opposition to one another until Christ returns. Is there not a more excellent way? (1 Cor. 12:31).
Love for Christ must include a love for His truth, and so we can never treat as inconsequential anything that Christ has commanded. Only those who abide in Jesus’ word are truly His disciples (John 8:31), and disciples are to be taught to obey all that He has commanded (Matt. 28:19–20). So the route that we might call doctrinal minimalism is not open to us. We cannot simply reduce the number of doctrines to be taught and believed to what we can all accept as important and ignore the rest. Movement in that direction always seems to lose its brakes and eventually nothing distinctive of Christianity remains.
But neither can we lock ourselves up in very small groups with maximal agreement on doctrine and morals, and then separate from others and refuse to acknowledge as Christians those who do not embrace all our distinctives. The multiplication of small groups who pride themselves on purity but who denounce and despise those who fall short of that standard does nothing to express the truth of “the one, holy, catholic, and apostolic church” for which Christ died. The love we must have for all of Christ’s disciples has no expression in this path. Where, then, is the more excellent way?
As we have observed above, the unity that we have is by the Spirit of Christ baptizing us into Christ and into His body, the church (1 Cor. 12:12–13). Our expression of that unity must therefore be a unity of the truth “as the truth is in Jesus” (Eph. 4:21). Ultimately, that will be all the truth that is in Jesus, but our unity with Jesus does not wait until that perfection is achieved. Salvation comes to us by faith in Christ, so there must be a defining core of truth that is ours in faith, sufficient to unite us to Christ even if not yet complete in all its detail. Defining this core precisely might prove to be as difficult as living out the whole truth faithfully, but it will surely include that God, the creator of heaven and earth against whom we have all sinned, was in Christ, reconciling to Himself all who believe in Him, not counting their sins against them, but forgiving them through the redemption that is found in the sinless life and atoning death of Christ and received by faith alone, calling for obedience to Christ as Lord under the authority of His Word in the Holy Scriptures. Where Christ is truly preached, there is the gospel; and where the gospel is truly believed, there is the church.
Yet as we have seen, the church that is in Jesus is a diverse church. This diversity among Christians is due to our lack of conformity to Christ. He has chosen to sanctify us gradually in this world. As the progress we make in sanctification varies both in doctrine and in practice, there will always be a need in this world for those who are united in Christ to live in love with one another while dealing with differences. Sometimes these differences result in the formation of different churches and denominations in order to maintain a good conscience toward God. But such divisions need not be a defeat of unity among us, so long as we do not permit them to destroy our love and welcome for one another in Christ. Some divisions are of practical necessity anyway, for not all Christians in the world can meet together at the same time in the same place.
Many distinct gatherings of Christians spread throughout the world can actually serve the purposes of God, by sprinkling us among the lost to shine the light of Christ. Our multiple groupings can also serve us well, encouraging us to be faithful to what we believe Christ has taught us, bringing us together with those with whom we can cooperate most fully. But if we allow our divisions to become breaches of love and occasions for pride and rivalry, then we will have failed in our calling, and our witness for Christ will be marred.
The saying of Rupertus Meldenius strikes the right balance. It calls for unity on the essential things, the core of truth in our union with Christ. In non-essentials (not the unimportant, but those things that if lacking do not prevent our union with Christ), it calls for liberty so that all might follow their consciences under the Word and Spirit. In all things, however, there must be love (“charity” from the Latin caritas, or “love”), “which binds everything together in perfect harmony” (Col. 3:14).
May the God who gives endurance and encouragement give you a spirit of unity among yourselves as you follow Christ Jesus, so that with one heart and mouth you may glorify the God and Father of our Lord Jesus Christ. Accept one another, then, just as Christ accepted you, in order to bring praise to God (Rom. 15:5–7).