By the time those stories boiled over, they were generally not even covered by religion writers.
In fairness, he's not shy about praising the work of the many journalists he feels have excelled at religion coverage: the late David Shaw of the Los Angeles Times, whose 1990 series on how bias shapes religion coverage is "the definitive document;" a "hero," Russ Chandler of the same paper, and Peter Brown, an Orlando Sentinel columnist who wrote a book analyzing the lifestyles of American journalists and how they shape coverage of religion.
It was so complex and controversial, he says, it never found a publisher.
"I told him, 'Peter, if you'd given it the right title - Baby Boomer Urbanites From Hell - things would have been different,' " Mattingly says with a laugh.
As he sees it, Christians share the blame for the news-religion gulf. A seminary graduate, he says the students he works with from religious colleges around the country are so used to "getting ignored and beat up" by newspapers, they often show up in Washington hating and fearing the secular media.
He doesn't advocate "affirmative action for born-again journalists" but rather encourages young believers to get familiar with the profession so they can enrich it from within. Graduates from the four-year-old program are working full-time at newspapers from California to Tennessee.
Monklike in his full beard and glasses, he pads into the tiny study in his home's basement, a room that evokes the impishness with which he sometimes views his work.
"I Strangled Shirley MacLaine In A Previous Life," reads a bumper sticker on a cabinet.
"Dude, she can be annoying," Mattingly says of the actress who claims to have been reincarnated many times.
Soon he'll be banging out next week's 750-word column - he hasn't picked a subject yet - and he's devouring Harry Potter's Bookshelf: The Great Books Behind the Hogwarts Adventures, a new tome by a friend, John Granger, that argues J.K. Rowling's books are, in effect, Christian apologetics in disguise.
David McHam, a longtime journalism professor at the University of Houston, says an underrated facet of Mattingly's work is his reporting.
"He has an insatiable mind, and he knows how to get the good stuff," McHam says. "I don't know how he does it every week."
To Van Biema, the work has paid off over the years, as Mattingly's critiques have helped sensitize mainstream religious coverage - even now, at a time when newsroom cutbacks are making religion writing a rarer commodity than ever.
