Frank Schaeffer is the author of the novels Portofino, Saving Grandma, and the sequel Zermatt, which will be published by Carroll & Graf in October. The son of Presbyterian apologist Francis Schaeffer, Frank has now written a nonfiction book with his own son, John, titled Keeping Faith: A Father-Son Story About Love and the United States Marine Corps. The book has been receiving attention from several quarters (including Oprah Winfrey's TV show), and is number 30 on The New York Times hardcover nonfiction bestseller list.

What is it that people are connecting to in this book?

This book tells the story of a guy who lived in the Volvo-driving, higher-education worshiping Northshore Boston. It tells the story about a family who had never imagined one of their kids going into the military. My older son went to Georgetown, and my daughter went to New York University. John wanted to go into the Marine Corps right out of a swanky private school. I had never served in the military, and, to be frank, the children of the members of my economic class—white, educated, '60s-generation types—usually don't serve, at least not around here in Massachusetts. We leave military service to other people's sons and daughters.

Why do we assume that Chelsea Clinton or Jenna Bush aren't going to volunteer for the military, whereas it doesn't surprise us if we hear that the guy who works down at the gas station has a son in the military? In World War II everybody did the heavy lifting, not just the less-educated echelons of the society.

I guess what people are connecting to with Keeping Faith is a personal story about a father who loves his son and the son who loves his father fighting all through the last summer. The kid was at home. I didn't like his ...