As long as I can remember, I have heard Baptists talk about "the autonomy of the local church." It is a tenet of faith for most of us. In an article published by Associated Baptist Press http://www.abpnews.com/www/2469.article.print, Beth Newman comments on this idea from the perspective of a recent Baptist World Alliance symposium. She observes that the most important statement to emerge from that meeting was, "We affirm that for Baptists the local church is wholly church but not the whole church."
I may unpack this more in future postings, but this is an important concept. Although we celebrate the opportunity and responsibility of each local congregation to "discover and fulfill its God-given mission" (in CBF terms), we must not forget that each congregation is just one small part of the bigger picture that God is creating that is the Kingdom or Reign of God. Just like a massive mosaic made up of many colored tiles, all are necessary to make a coherent picture. Certainly, a few holes here and there may not be a problem, but the picture would be so much better if all the parts were present.
Each congregation must find and pursue its mission, but it must also consider how that fits into the bigger picture and determine how God may be calling it to join with other congregations to compose the total picture of God's mission in the world.
Our churches are indeed autonomous but that does not mean that they don't need each other!