Why does this keep happening?

I really don’t understand why this keeps happening. Over the last 15 years or so, I keep getting hired to do jobs that I’m not really very qualified to do, even when I keep saying that there are others who are far more qualified. How in the world do I keep finding myself in this position?
But, the jobs I really want to do (like a full-time ministry position – on a university campus, perhaps) I can’t seem to get.