Some of the most fruitful times I've experienced in church staff meetings have been those occasions when we've thought through the theological foundations for why we do what we do. Obviously, there's an abundance of tools for generating those conversations, not least among them, Scripture itself.
One non-inspired book that I've found to be unusually helpful for guiding our examination of pastoral ministry is Charles Bridges' The Christian Ministry. You won't agree with Bridges across the board. You certainly shouldn't. But it raises a wide range of important conversations. It's also an old book, and a significant advantage of using an old book is that we can explore the underlying, abiding principles that shape our ministry while maintaining some distance from the pressures that perpetuate our allegiances to our traditions.
I've just learned that the book is now available in paperback at a much lower price than the Banner of Truth hardback. And it's on Kindle for less than $1.