In the movie The Blues Brothers, Elwood proclaimed throughout the movie in his exaggerated Chicago accent, "We're on a mission from God." Jake and Elwood were on a mission to raise enough money to save the orphanage where they had grown up. Through all their escapades, as they reunited the members of their band, as they evaded police, klansmen, and women scorned, as they performed on stage, they continually came back to "We're on a mission from God."
One might not exactly agree with their methodology, and one might even question whether their sense of mission was of God (although I seem to recall James saying something about caring for widows and orphans), but one would have a hard time denying that they remained motivated by their mission.
There is a lesson there for us as we seek to become missional. If we become convinced and convicted that we are on a mission from God, we might take a few risks and we might step outside our comfort zones. That may be what a missional church is - one who says, "We're on a mission from God."