A few years ago, someone developed a rating system for Unitarian Universalist sermons based on the movie rating system. I do not know the original author.
"G" Sermons: Generally acceptable to everyone. Full of inoffensive platitudes; usually described as "wonderful" and "marvelous." The minister panders to the congregational prejudices, while planning on a long tenure. It is always forgotten by 12:30 in the afternoon.
"GP" Sermons: For more mature congregations. It is sometimes relevant to today's issues. It may even contain mild suggestions for change. Often described as "challenging" or "thought-provoking," the minister is a safe prophet.
"R" Sermons: Restricted to those not upset by the truth. This sermon "tells it like it is." It is threatening to the comfortable and most often described as "controversial" or "depressing." It suggests that the minister has an outside source of income. Visitors are shocked.
"X" Sermons: A limited audience. It really "socks it to them." It is the kind of sermon that landed Jeremiah in the well, got Amos run out of town, and set up the crucifixion of Jesus. Always described as "in poor taste," the minister who preaches this sermon should have a suitcase packed and his life insurance paid.
Gilbert K. Chesterton said, “It is the test of a good religion whether you can joke about it.”