In my book Your Church Is Too Small I try to show how the unity of the church, established in Christ’s love for his Father, leads to a growing relational unity that follows him into his mission to the world. When this love happens in us we have what I call missional-ecumenism. The call to follow Jesus in his mission requires us to actively preserve the unity we already share in union with Christ. This prayer for unity in mission does not mean that we “win” some battles while we “lose” others. What I learned in the early 1990s, after I received this vision of a “big” church, was that all of the great traditions of the Christian faith, throughout the entire history of the church, have vital elements of truth in them. These elements should all be honored and preserved. When we adopt a zero-sum game – in which the winner takes all – then our gifts and diversity become the basis for more division and disrespect. A better understanding of our gifts, and the nature of our respective missional communities, would help us truly advance the kingdom of God without condemning and attacking one another in the process. “Diversity will, in fact, be a true hallmark of a unified community of believers. But for this to happen there must be a genuine love and trust among all the members, and that will necessarily involve genuine forgiveness for past failings” (Demetrius Dumm, A Mystical Portrait of Jesus: New Perspectives on John’s Gospel. Collegeville, Minnesota: The Liturgical Press, 2001, 78).
Because of John 17, and the importance of this prayer for understanding the whole will of Jesus for all his followers in every age, I have embraced what I would now call deep ecumenism. This does not mean that I deny aspects of truth in order to seek for a lowest common-denominator form of unity. When John says that Jesus came into the world as the Word “ full of grace and truth” (John 1:14) he expressed the same tension that we find in our pursuing truth when we vigorously seek to maintain unity.
Paul also expressed this “grace and truth” tension when he appealed to the churches in Ephesus to be one in Christ. He urged these believers “to make every effort to maintain the unity of the Spirit in the bond of peace” (Ephesians 4:3). I once preached in a badly divided church for eight months. I preached these same words from Ephesians 4:3 for four consecutive weeks! I had never done that before but in this instance I wanted to do everything I could to plant this divine principle deeply into the hearts and minds of these dear people. I explained to them that true ecumenism (the work of seeking for a realized and visible unity in the Spirit) involves more than a bare desire to find common ground in our doctrine, worship and prayer. It certainly includes sharing in Christ’s works of mercy and charity in the world together. But it has to mean so much more if we are determined to truly “seek first his kingdom” (Matthew 6:33). I am not sure how many of those precious people received the message that I brought to them over those four weeks. I am sure of this – I have never been the same. The preacher did get the message, as is so often the case, whether the people did or not!