The Whole of Christianity by C.S. Lewis

"This is the whole of Christianity. There is nothing else.
  It is easy to get muddled about that.
  It is easy to think that the Church has a lot of different
  objects-education, missions, holding services... The Church
  exists for nothing else but to draw men into Christ, to make
  them little Christ. If they are not doing that, all the cathedrals,
  clergy, missions, sermons, even the Bible itself, are simply a
  waste of time. God became man for no other purpose.
                                                       
                                       -  C. S. Lewis, Mere Christianity