It's one of the things ministers are supposed to do, along with comforting the afflicted. At its most simple, this 19th century aphorism reminds ministers to do their pastoral care and their prophetic preaching, 'cause their sick folks are afflicted and need comforting and their pew-sitters are too comfy and need afflicting with the world's injustices.
Young ministers quickly discover that that's way too simple. There are some people who are way comfortable with their afflictions and will soak up all the comfort a new minister can give and still need more. There are some pew-sitters who are in so much pain only an ogre would afflict more.
There are some UU ministers who feel uneasy ministering to UU's, who tend to be among the knowledge and professional classes. Way too comfortable by the world's standards, they all have enough to eat, shelter, and heat, the majority have health insurance, especially if they are over 30, and an awful lot can entertain themselves in all the ways their hearts desire.
The world's standards are very low, and frankly, I think of my folks (and myself) as afflicted in spite of their relative wealth. They are afflicted with all ills the flesh is heir to and are often rather isolated. Their lives are way too busy and terribly stressful, the younger ones often carry huge debt, and most are puzzled and uneasy, if not downright frightened, by the current state of the world. I call that afflicted. Most of my preaching is aimed, not at afflicting the comfortable but offering a word of understanding and healing to the afflicted.
We talked some, at the growth consultation, about how we deal with the prophetic side of ministry, and this was an area in which the 12 ministers of growing church clearly had different philosophies. Some do a lot of teaching about social problems and organizing of social change opportunities. Most of what you read about church growth suggests that this is crucial, but Social Justice has never been this church's strong suit, and it has grown anyway. I preach on social issues on the occasions when I think I have an insight to share. Sometime I just share my puzzlement and talk about how to live with fear. What I never do is just wring my hands, or wave my fists, sermonically. If I can't wring some hope and a to-do list out of a situation (the Iraq war comes immediately to mind), it's not fodder for a sermon, it's fodder for the prayer.