This is a video put together by Peter Dominey from Church from Scratch (a Baptist church plant) and he's asked me to post - knowing perhaps I might not wholly agree with it.
I'm trying to work out exactly what I make of it. It certainly is thought-provoking - what is the wall? - is it church buildings (Church from Scratch don't have one) or it is it something more along holiness lines (church holy/world unholy). As John Flett says in his fantastic The Witness of God, following Barth, there is no other way for the church to be but missionary. This critique of church, offered by this video and others, I sometimes think is too negative about church and it avoids the theological questions of what is church and ultimately that all communities have boundaries of one sort or another. It also suggests that a church like the one in which I minister is not somehow engaged in mission.