What right do I have to speak?
I don't think preaching should be, 'You know I was thinking the other day...' nor should it be a journalistic opinion piece on the events of the world. Sure, everyday life and our reflection on it can be revelatory. I completely believe that. But if that is the case then why should only one person be speaking? If our own reflection on life is where authority comes from then we should have something similar to the Quakers when all can stand up and deliver our thoughts. I don't see why two or three years at a theological college should qualify someone to stand up and dominate the conversation for 10, 20, 30 minutes.
See my own life and yours are full of revelation, sure. But there were some folks who really got to some religious truth, they discovered some amazing truths and told other people about it too. Why should we reinvent the wheel looking for revelation only in our own lives when others have found some powerful stuff that might be able to help us?
The only justification I have for standing up and talking at people for 10 (rarely more than 15 for me) minutes is that I have spent a few hours during the week wrestling with some of the Great Tradition. I have also spent (personally) four years full time studying the Great Tradition. Because of the time I have given to this (that other people do not have in their own lives) I can offer a sermon to other people to give them a head start in their own path of faith.
I cannot stand up and speak from my own authority. The only authority I have is as a transmitter of the Great Tradition. As much as I have studied the Great Tradition more than others I have the right to speak to others. But if I'm just offering reflections from my life without reference to the Great Tradition then I have no more right to speak than anyone else.