The church exists ... why?

What do you think about this statement on the purpose of the church and . This is a quote from Brian McLaren's 'A New Kind of Christian'.

"The church exists ... to be a catalyst of the kingdom. In other words, it doesn't just exist for its own aggrandizement. It exists for the benefit of the kingdom of God, something bigger than itself. Of course the church must grow, numerically and spiritually, but that growth matters so the church can become more and more catalytic for the kingdom of God, for the good of the world. This means that the world doesn't exist for the benefit of the church, as if the world were a mountain that we strip-mine to get ore to process in our spiritual factory, for the church's enhancement. No, the church exists for the world - to be God's catalyst so that the world can receive and enter God's kingdom more and more."