Who is the church for?

In his online class notes on Acts 15, Prof. Conrad Gempf refers to the story of a young Bill Hybels being fired from his youth pastor position "because his group was attracting the wrong kind of kids." Conrad takes issue with his course textbook author who asserts that the church is for outsiders:

If the question is "Who is the church for?" isn't the real answer that it's for God? Have we lost that focus? Acts 15 does not say that the church is for the people; it's inclusiveness consists of this: that anyone who is ready to follow the Lord Jesus Christ should be welcomed and they don't need to become just like us.

But there is more to the Acts 15 compromise than inclusiveness. There are demands as well. (The chapter is not, of course, about outsiders who are unbelievers, but those from a Gentile background who have committed themselves to Christ.) New believers from a pagan Gentile background do not need to turn themselves into Jews but neither may they remain pagan Gentiles (15:19-31). I wonder if we've misunderstood Bill Hybel's critics: were they really worried that church was attracting outsiders or were they worried that the church was coming to be made up of people whose lives were no different from unbelievers?

A big frustration for many Christians today is that the lives of Christians as a whole are not much different from the world at large. Could it be because we've paid too little attention to repentance and sanctification?