I think 'sustains' is the key word here, church should never be a monopoly of a few and doesn't make much sense outside of relationships working and supporting one another. Each other's gifts and contributions are what sustains church and it seems that it is from generous and honest relationships that they emerge. It is not surprising that Robert Warren turns to Ephesians 4 and the body of Christ to illustrate our responsibility to each other and our responsibility to step up and help the church function properly.
Jumping around the marks we land on #6 Makes room for all which is all about being inclusive rather than exclusive. This is about extreme hospitality and embrace and definitely has close links with having an outward focus. What is generous inclusion really about? How should it shape us as a church?