How important is the size of a congregation’s membership? Here’s Kennon Callahan’s response:
“Regrettably, in many of the churches in our country there is a preoccupation with membership. A simple illustration will suffice: Two ministers meet at a conference. The one minister is in the process of moving to a new pastorate. The other minister, in an almost automatic way, asks, ‘How many members does your new church have?’ The more important question would be, ‘How many people is your new church serving in mission?'” (Kennon Callahan, Twelve Keys to an Effective Church, 1st ed., Jossey-Bass, 1983, pp. 2-3.) And what does Callahan mean by “mission”? He defines it thus: “…in doing effective mission, the local congregation focuses on both individual as well as institutional hurts and hopes.”
Of course it’s more complicated, and more nuanced, than these bald statements would imply. For the complex, nuanced version, you’ll have to read the first chapter of Callahan’s book yourself.