Here are several seminal statements about the church from Karl Barth’s "Church
Dogmatics" as cited in the book, The Witness of God; The Trinity, Missio Dei, Karl Barth and the Nature of Christian Community .

“The community is alive, there, and only they are, where she
is engaged in recruitment and when she strives for this recruitment especially
in the apparently darkest areas of the world: in places where the Gospel is
still completely unknown or completely rejected, in medio inimicorum. The community is this such a missionary
community, or she is not the Christian community.”

“[T]he community which has not existed in the interim period
as a missionary community as such, whose witness has not been invitational or
persuasive according to the measure of her power, with the return and final
revelation of her Lord will be banished into the darkness, where there can be
only wailing and gnashing of teeth instead of the promised banquet.” 

 

A summary statement by the author, John Flett:

“Mission is not a second step in addition to some other more
proper being of the church, because, as the living one, God’s relationship to
the world belongs to his eternal being. The Christian community is, as such,
the missionary community, or she is not a community that lives in fellowship
with the triune God as he lives his own proper life.”

These concepts and these statements are obviously related to
a Trinitarian view of theology. The concept of the Trinity informs all of the
language of the "missio Dei." Hopefully, as these quotes are communicated on my blog
you will get a more full or complete understanding of what it means to be
Trinitarian, living the life of God in specific context or place.