One of my friends posted this article on Facebook this week: http://newsweek.washingtonpost.com/onfaith/Non-Believing-Clergy.pdf. It is essentially a study of five anonymous Protestant ministers who define themselves as (in some sense) non-believing. Of course, their congregations don't know that. "Coming out" as agnostic or atheist when you are a minister would be tricky, to say the least. Our vocation - and practically speaking, our ability to earn a living - rests on our ability to maintain faith.
Given that we all supposedly go into this field based on a sense of calling, you may not think that would be a difficult thing. But then you go to seminary, and they intentionally rip up all the things people assume to be true about the Bible and God, and most ministers come out of seminary with a much different picture of faith than they did when they entered. Then you get into the church, and you can't preach all of those things you learned in seminary, because your parishioners are going to think you're a godless heathen if you start spouting things about different authors and two versions of the creation in a sermon. And maybe you try to teach a class so you can talk about these things in an environment where there is the time and space to take people along gently, but chances are, two people show up and they're the ones who already wonder about all of this literalism business. So there ends up being this gap between what ministers actually believe, and the way they communicate with the people in the pews.
On a side note, I actually work in a church where it's totally okay for me to assume that the Bible didn't fall from the mouth of God and question the things in it. If I didn't, that's probably when I'd be fired. But that isn't the case for most of my clergy brethren and sistren. And then we all have to deal with this side of the church that is not at all about sacredness or reflection or community or any of the things people seek in churches. We spend a lot of time dealing with budgets and newsletters and angry people who shout at us (or more likely slander us behind our backs) about very petty things. It doesn't really encourage a high level of piety or reverence about church things.
I don't have this problem with struggling over non-belief. I believe...although exactly what I believe varies somewhat depending on the day, and I do struggle with maintaining integrity in a job where the expectation is that I will tow a theological line. I wonder what I will do if, at some point, I am subjected to a doctrinal litmus test. I suspect many people would say that I am not reverent enough, that I don't have enough respect for church traditions, that I am a bit of an iconoclast. I know lots of ministers who feel the same way I do but don't act on it. I suspect that feeling irreverent about the church is a professional hazard, like funeral directors who joke about death. Which they do, by the way. If you've never hung out with funeral directors, you should; they're usually hilarious - but only if you can handle a complete lack of respect for all things sacred.