The reason, nature and source of Christian unity

“It is to be numbered among the evils of our day, that the churches are so divided one from another, that there is scarcely any friendly intercourse strengthened between us; much less does that holy communion of the members of Christ flourish, which all profess with the mouth, but few sincerely regard in the heart.” (letter from John Calvin to Thomas Cranmer dated 1552 responding to Cranmer’s idea of an international protestant council) 

May the God of endurance and encouragement grant you a common mind among one another, in accord with Christ Jesus, that together you may with one voice glorify the God and Father of our Lord Jesus Christ. (Romans 15:5-6)

That is a prayer that I’m praying repeatedly at the moment and coming to love more and more.

It tells us the great reason for Christian unity – worship. It’s not just that unity is a joy (it is) or that it is more effective (it can be). What glorifies God the most is when people of every accent and culture all sing praises in unison to the one Triune God. It proves that he is not a tribal deity or colonial convenience. It proves that he doesn’t just appeal to a certain aesthetic or personality type or class or stage of development.  When, one day, representatives of every single people group all shout in agreement that God is utterly beautiful and satisfying it will prove beyond doubt that he is the desire of every nation, the dazzling jewel in the eye of every beholder viewing from every angle.

That’s why, in the verses following Paul’s prayer for unity (Rom. 15:9-12), he piles up verses from the Law, the Psalms and the Prophets all speaking of the Gentiles, together with the Jews – all peoples – praising the God and Father of Jesus the Messiah. That’s the reason for the unity – not as an end in itself but to the end that God looks great as he is praised by all nations and satisfies the hopes of all nations. We are to “welcome one another for the glory of God” (v7) – so that there is a church whose joyful diversity and worshipful unity can only be explained by the gospel.

The prayer in Romans 15:5-6 also tells us the unique nature of Christian unity – a common mind in accord with Christ Jesus. There are at least three important things going on there:

1. Christian unity is internal before it is external. One mind (v5) comes before one voice (v6). This is not an imposed unity or a mindless chanting of a common formula. At the centre of Christian unity is unity of heart and mind in the faith and knowledge of the Son of God. That’s why Paul has been so keen to write this long letter to the Romans packed with detail about the gospel of Christ, because he knows their unity must stem from a unity in the complex substance of Christ crucified and risen and returning and united to his people. He wants them to have a common gaze fixed on Christ, a common heart that is thrilled by Christ, a mind that wants to know nothing but Christ and him crucified and how everything in the universe relates to him.
2. Christian unity is not only centred on Christ, it is also modelled on Christ. Or to put it another way, an important part of being centred on Christ (‘in accord with Christ’) is that the pattern of Christ shapes the manner and determines the dynamics of Christian unity. Look at the context. In Romans 15:1-2 Paul sums up what he has been saying from the beginning of chapter 14: “We who are strong have an obligation to bear with the failings of the weak, and not to please ourselves. Let each of us please his neighbour for his good, to build him up.” And then Paul explains that this forbearance and concern for others is in accord with the pattern of Christ Jesus: “For Christ did not please himself.” And immediately after the prayer for unity Paul says: “welcome one another as Christ has welcomed you… for I tell you that Christ became a servant to the circumcised” (v7-8). So in Romans 15:5-6 Paul is praying something very similar to Philippians 2:1-11 – have the same mind among you and may that be according to Christ Jesus – in the sense both of a deep unity of fellowship in Christ himself and in the sense of having the same mind as Christ had in that he didn’t look to his own interests but to the interests of others, taking the form of a servant and humbling himself to death (that every tongue would be united in one voice to the glory of God the Father).
3. The dynamics of Christian unity are also the dynamics of mission. Once we see that Christian forbearance and flexibility is modelled on Christ we start to see that it is not limited to those who already confess Christ. Yes the emphasis in Romans 14 is on relationships between those who belong to the Lord, but in chapter 15 the emphasis shifts towards gathering in others from all nations. Christ bore the rebukes of unbelievers (v3). His servanthood (v8) was for the sake of the lost. In the second half of chapter 15 Paul arrives at the point of his whole letter which is to get the church in Rome excited about partnering with him in his mission to Gentile Spain (v24). The movement in Romans 14-15 is actually remarkably similar to 1 Corinthians 8-10: an appeal to the strong not to destroy the weaker brother (Ch. 8) then an explanation that selfless, freedom-forgoing servanthood is not only to be towards brothers but it is also the posture of cross-cultural evangelism – becoming all things to all people in order to save some (Ch. 9) and all this carefulness in regard to conscience, unity and stumbling blocks is in accord with Christ and to the glory of God (Ch. 10). So ‘in your eating or drinking, or whatever you do, do it all to the glory of God, giving no offence to Jews or Greeks [unbelievers] or to the church of God [weak fellow believers]… please others not seeking my own advantage… be imitators of me as I am of Christ’ (1 Cor. 10:31-11:1).

How do we get this? Where does this kind of Christian unity come from?  Wonderfully, Paul’s prayer in Romans 15 also tells us the root source – endurance and encouragement.

• We need endurance – perseverance, patience. By definition 'endurance' is in the face of hard stuff. Pursuing peace (Rom. 14:19 cf. Psalm 34:14) is a long and difficult road. Bearing with one another’s failings (Rom. 15:1) is uncomfortable. It’s much easier to only work with those Christians who have the same ministry culture, who operate in roughly the same way and have much the same opinions on most things. But when we pursue conversations and partnerships and working together beyond that circle then it is harder work. To get in a room together and talk through the nitty gritty of divergent ministry methodologies, listening to each other carefully, teasing out differences of expression and culture from genuine differences of substance and assumptions – and doing all that in a way that honours Christ both in graciousness of manner and in reverence for infinitely precious gospel truth – that is tough, tricky and time-intensive. Calvin knew that and in his reply to Cranmer (quoted above) he speaks of his willingness to ‘cross ten seas’ even if it was only for the unity of English Protestants. For the goal of an even wider Christian unity he says, ‘it would be a crime in me to spare any labour or trouble to effect it.’ That's endurance.
• We need encouragement – comfort, joy. That’s the other essential ingredient. The old commentator Matthew Henry says, ‘nothing breaks the peace more than an impatient and peevish and fretful melancholy temper.’ In contrast, nothing fosters Christian unity more than a heart that is happy, secure, humbled and encouraged in Christ. And it's encouragement that all Christians need for their own souls as they pursue peace in their churches and between churches. When peace-makers are bruised, discouraged, rejected, misunderstood or simply mess up or fail on the tortuous road to Christian unity, they need the great comfort of the gospel – yes we are sinners, failures and fools but Christ came into the world to save sinners, failures and fools, he took our punishment, we are his, the Father smiles on us as his children. And peace-makers also need a gospel-wrought positivity, optimism and expectancy. The council of despair is – there is no way that we can work together, evangelicals are irredeemably tribal, we’ll never agree, let’s just plough our own furrow. Certainly there will probably always be disagreements over baptism and ecclesiology until Christ returns. But a gospel-wrought positivity says – the gospel really does break down barriers, grace is stronger than sin (Rom. 3-8), not by might nor by power but by the Spirit of the Almighty mountains can be removed (Zech. 4:6-7), he can do more than we ask our imagine to bring glory to himself through the unity of his people (Eph. 3:20-21) – primarily in local churches but also in the one body of Christ.
• We need both endurance and encouragement mingled together. Endurance without encouragement could be a grim slog, miserable servanthood. Encouragement without endurance could be an enthusiastic but short lived attempt to ‘jolly everyone along’. Both together they produce joyfully persevering servanthood. 
• We need God to give us endurance and encouragement through the Scriptures. All the commentators notice that the same words – endurance and encouragement – are mentioned in verses 4 and 5 of Romans 15. In verse 4 they come through the Scriptures as the ‘conduit-pipe’ and in verse 5 they are found in God the ‘fountain-head’ (Matthew Henry). Amazingly the Holy Spirit had every word and phrase of the Scriptures written specifically for us (NT believers) and specifically that he might, through those words, give us the endurance and encouragement that we need. So the pursuit of Christian unity must involve open Bibles and desperate hearts. The Scriptures and the power of God.
• We need God to give us endurance and encouragement through seeing Christ in all the Scriptures. That’s perhaps the most striking of many striking things in Romans 15. Just before Paul says that ‘everything was written for our instruction’ he gives an example – Psalm 69:9 – the words of a persecuted man – which he unequivocally reads as Christ speaking in the first person. That’s one way we find Christ in the Scriptures – speaking in the first person. Another way is when he is spoken of in the third person, as Paul finds in Isaiah – ‘the root of Jesse’ in whom the Gentiles hope (Rom. 15:12). And another way is when we see Christ as the fulfilment of the covenant of grace with the patriarchs (Rom. 15:8). There are all sorts of ways in which we find Christ in the OT but find him we must because it is when we behold him, crucified and glorified, in the pages of Scripture that we receive the endurance and encouragement we need. It is as we read, for example, the Psalms and see Christ thirsting and forsaken and oppressed and soaking his bed with tears and crying out to the Father and defeating his enemies and ascending into heaven and seated on the throne – as we look to Jesus, in joy enduring the cross and despising its shame (Heb. 12:2), enduring from sinners such hostility and reproaches (Heb. 12:3; Rom. 15:3) that is when we receive encouragement and endurance - what we need for God-glorifying Christian unity.