Why do people stop growing?  Why do Christians stop growing?  Christians stop growing because they have stopped pursuing the heart of God.  Just that simple.  It is best illustrated in the book of Jonah.  God tells Jonah to go to Nineveh and preach judgment against so that they people will repent.  Jonah takes off another direction.  Why?  Because he wanted God to destroy Nineveh.  He did not have the heart of God.  For a prophet, that is disastrous.