I can think of few more dangerous ideas in the history of  humanity than the assertion that God calls people to preach.  How many preachers have there been who felt called by God to  preach bigotry, violence, and the denial of scientific discovery?  The bloody record left behind by the preaching of ignorance and  hatred is enough to make any thinking person question whether  the world might not be better off if we dispensed all together  with the idea that God calls human creatures to preach. And yet... and yet I think of preachers who have rallied people to act  for justice, to embody compassion, and to give witness to  the love and grace of Christ.