"A 'missional' small group is not necessarily one which is doing some kind of specific 'evangelism' program (though that is to be recommended) Rather,
1) if its members love and talk positively about the city/neighborhood,
2) if they speak in language that is not filled with pious tribal or technical terms and phrases, nor disdainful and embattled language,
3) if in their Bible study they apply the gospel to the core concerns and stories of the people of the culture,
4) if they are obviously interested in and engaged with the literature and art and thought of the surrounding culture and can discuss it both appreciatively and yet critically,
5) if they exhibit deep concern for the poor and generosity with their money and purity and respect with regard to opposite sex, and show humility toward people of other races and cultures,
6) they do not bash other Christians and churches
--then seekers and non-believing people from the city A) will be invited and B) will come and will stay as they explore spiritual issues."
Tim Keller, The Missional Church (read the full article here)