My wife (an irreverent theologian, to be sure) asserts that "missional" is not an English word, but some theological babble that people noise about today. Yes, I admit that the word doesn't appear in my Webster's 10th edition, but contemporary writers are using it to describe the basic theological conviction that God sends the church into the prophetic task of witness and service. ("Missional" comes from the Latin missio, which means "to send.") More importantly, these writers are drawing us back to what Jesus directed us to do: To live for the benefit of others, not ourselves. Too often, the church is pathetic and not prophetic.
Thankfully, when I turned to Karl Barth (the greatest theologian of 20th century), I found all the theology I needed and nothing called "missional." Barth believed that in Jesus' role as Prophet, he sends his community into the world in service (Church Dogmatics IV/3.2).
I'll let the Swiss theologian Barth speak for himself (though translated, of course): "The Holy Spirit is the enlightening power of the living Lord Jesus Christ in which He confesses the community called by Him and His body, i.e., as His own earthly-historical form of existence, by entrusting to it the ministry of His prophetic Word...."
I'd let to know what you think of them Apfels.