I don't like this question and I know the interviewers are sincere in asking, but my most honest answer is: Whatever God wants. I'm not smart enough to figure out how my writing will touch others—if it does.
For example, I wrote 90 Minutes in Heaven for Don Piper. Most positive comments came from people who spoke about their powerful or peaceful response to Don's description of heaven. However, a large number of people responded in a way that surprised me. The first one was from a man who said, "Thank God, someone understands chronic pain and has the courage to write about it." Others resonated with that same idea.
I wasn't insightful enough to anticipate that response, but it amplifies my answer: Whatever God wants.
That doesn't mean I never have anything in mind, but often I have to be asked the question before I figure it out. This is the response I gave to the ezine interview mentioned in a previous blog about my book When a Man You Love Was Abused: "I want to help women who know or suspect that an important man in their lives was abused. They also need to realize that his victimization affects them. I hope women will share portions of the book with those men who might not otherwise seek help."
Again, when I ponder the wide level of responses, most of the readers—male and female—tell me that what they liked best was that I talked personally about problematic topics few people dare to mention. They identified with many of my issues.
But here's one answer that covers every book I write:
I write with transparency
to encourage others to face their own issues.