…and you preached to me about penal substitutionary atonement. I was sick and you said a Biblical understanding of leadership would bring me comfort. I was in prison and you sent me a book on the Biblical understanding of membership. [link]
There is a point at which Leeman's missional slippery-slope argument borders on the insane – or at least, the asinine.
Studying this might alleviate said issues.
UPDATE: And Todd Littleton has a good post on slippage.