"No temptation has overtaken you except what is common to us all," St. Paul wrote in 1 Corinthians 10:13.
If you're a preacher, and if you possess the slightest bit of self-awareness, that's problematic. It means that preaching against any temptation or sin implicates your entire congregation and yourself as well. That can be really uncomfortable for all involved. Pick any of the seven deadlies or the 10 commandments and you risk alienating everyone in the pews and exposing yourself as less than perfect. Awwwk--waaard.
But lately, many American evangelical preachers think they have found a loophole: Homosexuality. Here is a temptation that does not seem to be common to us all. It seems to be the perfect "sin"* -- the perfect safe target. Straight preachers can rail against it without worrying about exposing themselves as hypocrites or, even worse, as fallible humans just like everyone else. And statistically speaking, most of the congregation will be able to say "Amen" without squirming or feeling the least discomfort. It's all win.
Can't wait for part two.
EDIT: Here's part two.