John Flett, The Witness of God: The Trinity, Missio Dei, Karl Barth, and the Nature of Christian Community (Eerdmans, 2010): 296-7.
If the community is Christian only insofar as she is missionary, if the missionary act is the concrete form of divine and human fellowship here and now, then the lack of reference to mission at every level of the teaching ministry of the church is a frightful abrogation of theological responsibility. If it is possible for a ministry candidate to progress through academic training – as much within a seminary as a secular university – without any dogmatic attention given to the purpose for which the Christian community exists, then this indicates the community’s own radical disorder. Jesus Christ’s call for the community to be his witnesses cannot be relegated to some derivative status. Because mission is located in the doctrine of the Trinity, it must again return to theological curricula, must become central to the teaching ministry of the local congregation, and must inform liturgical practice. The entire community is to hear of the commission of her being and the declarative nature of Christian fellowship, to repent and intentionally move into the world developing missionary forms as she learns the obedience of the Spirit.