I was thinking I would weigh in later yesterday to Matt Kronberg’s solid, sensitive question. But (besides playing golf and spending the rest of my day working — if one calls what a professor does “work”), the conversation level was so solid I thought I’d wait until today. So here goes:
First point is a big one: it matters a lot less what we call what we are doing than doing what we are to do, and if we do that, it might not matter a whole lot what we call it. Call it “missional” or whatever, but if you are doing it, it will be enough most of the time.

Second, though: we humans are what Walker Percy (or is it Percy Walker?) homo loquens. That is, we are talking and speaking beings. No matter how well or how poorly we “do missional,” we will have to talk about it. (There’s a lecture here on Word leading to words and words being context-driven and limited, but I’ll avoid it.)
Third, the word “missional” captures some elements or our vocation in this world that call for this term the most:
1. The word “evangelism” has fallen on hard times because of the way it has been reduced by cheap tricks and limited horizons. This, too, requires fuller discussion, but not in the post itself.
2. The word “missional” roots what we do — whatever it is — in the “mission of God” (missio Dei). This is a major advantage of this term. Discerning what that mission of God is requires patient biblical, theological, and pastoral study and conversation … but discerning is worth the effort.
3. “Missional” expands the work of the Church to the horizons and depths and heights of the biblical vision — beyond curing the guilt issue and getting saints to glory, the term sweeps us into the work of God both in this world and beyond.
4. “Missional” widens the work of the Church to the whole Eikon — heart, soul, mind and strength — and to the whole society — church and culture — and to the whole world — including Ivory-billed Woodpeckers and global warming and the like.
5. “Missional” reshapes what churches are here to do: from gathering on Sunday morning from 11am to noon, with perhaps a SS class first, to seeing Sunday morning (with variation on times and days) as fellowship, worship, and instruction in order to glorify God by being swept into and sweeping others up into the mission of God for 7 days in a row.
6. “Missional”, for me, gets to the perichoretic heart of God. And here I tip the hand of some cards I’m now writing about: the perichoresis at some level speaks of the constant, eternal welcoming of each person of the Trinity by the Others and the ongoing sending/escorting of each person of the Trinity by the Other. Which means, to be missional means to participate in the perichoresis.
7. “Missional” focuses not only focuses on the width and breadth issues, but also focuses on performance. Frequently missional and emerging folks speak here of incarnation — and they mean the follower of Jesus is to live it out.
Therefore, brother, I like the term. Does it have its drawbacks? You bet. And yesterday Peggy got to the heart of it: If we were more perichoretic, others might simply think we were fine folks doing the work of God in this world for the glory of God and the good of others.