What is a sermon? Wrong question. A sermon is not a what but a who. A sermon is Jesus Christ expectorate. You eat the book; it is sweet in the mouth but bitter in the stomach (Rev. 10:9-11); you spit out the Word and spray the congregation. When grace hits the mark, it always begins with an unpleasant recoil.
A cheery image of a punk rock preacher gobbing at the congregation springs to mind — I hope it isn’t still there when I get into the pulpit tonight! There’s good stuff in the piece, well worth reading it all.