According to Kim it depends upon how you read Paul's first letter to the Corinthians. If you see the world from the perspective of the church, as hegemonic hierarchy, then you will understand ecumenism to be about unity. The Body of Christ is defined by belief, and boundaries are drawn between believers and non-believers.
For Paul though, according to Kim, the problem is not disunity but conflict between factions. His solution to power conflicts is reconciliation between diverse groups. This is achieved by living the life of Christ crucified rather than through belonging to a church.
Kim says on page 74:
Being united in the same mind and the same purpose is not a matter of belonging to an ecclesiological body, but rather is a matter of having a mind and purpose framed by the same gospel that does not empty the cross of Christ of its power.
For several decades in Britain, perhaps since the 1910 Edinburgh Mission Conference, ecumenism has focused on unity between Christian traditions. A great deal has been achieved in Britain and elsewhere. Besides the various Uniting and United churches there has been a general movement towards reconciliation between traditions. There is more to be done; there remain many people who are not convinced of the value of the ecumenical project. Others point to frequent failures and setbacks. But overall, a great deal of progress has been made. A return to the antagonism between traditions in the past is unthinkable.
But for many younger Christians, this success is closer to absolute. Many Christians no longer think of themselves as members of a single tradition. They work alongside other Christians, without awareness of doctrinal differences. It seems they no longer matter.
Neither the mainstream churches nor the informal congregations of younger Christians can be simply equated to Kim's contrasted understandings of the Body of Christ. What it does suggest though is that future ecumenism may need to focus upon diversity rather than unity. Some ecumenists speak of 'unity in diversity'; perhaps Kim's contrast between unity and reconciliation offers us a clue as to what is at stake.