In 1956, former President Harry Truman was asked by a priest in Rome what St. Francis had done for him. "Nothing," Truman jocularly replied, "but give me a sore throat and a stomach ache in his town of San Francisco."

Truman's response to the priest is provocative because it is the reverse of what you would expect a president to say. In general and throughout American history, presidents—for the most self-protective reasons—not only avoid comments that might offend a vote of faith as sacrilegious, but also tend to exaggerate the depth of their personal religious conviction and practice. Richard Nixon, for instance, kept Reverend Billy Graham close at hand and started regular, well-publicized prayer services at the White House—even though, as the later record demonstrates, faith does not seem to have loomed large in his approach to presidential leadership.

Truman's comment to the priest suggests that he was one of the rare past presidents whose seeming public nonchalance about religion concealed a deeper, more complex and more interesting reality: he was more of a Christian than people realized. The ignorance of Truman's peers about his private beliefs is not astounding because, in my experience, two facets of a president's private life that are among the most difficult to discern—either at the time or in history—are marriage and religion.

(CNN) -- The National Security Agency program that collects data on nearly every U.S. phone call isn't legal, a privacy review board said Thursday in a newly released report.

Moreover, the five-member Privacy and Civil Liberties Oversight Board said it's been largely useless in thwarting terrorism.

"We have not identified a single instance involving a threat to the United States in which the program made a concrete difference in the outcome of a counterterrorism investigation," the board wrote in the report released Thursday.

Despite Obama's NSA changes, phone records still collected

The board said it had identified only one instance in which the program helped authorities identify a terrorist in the last seven years. But the board said law enforcement would have found the suspect anyway, even without the NSA program.

The board doesn't have any legal teeth, so its recommendations won't change government practices the way a court ruling might.

But the findings are a stinging rebuke of President Barack Obama's legal defense of the program, in which the NSA tracks millions of telephone calls each day, harvesting the telephone numbers involved, the time calls are placed and how long they last.

For many of our contemporaries, no one sums up missionaries of an earlier era like Nathan Price. The patriarch in Barbara Kingsolver's 1998 novel, The Poisonwood Bible, Price tries to baptize new Congolese Christians in a river filled with crocodiles. He proclaims Tata Jesus is bangala!, thinking he is saying, "Jesus is beloved." In fact, the phrase means, "Jesus is poisonwood." Despite being corrected many times, Price repeats the phrase until his death—Kingsolver's none-too-subtle metaphor for the culturally insensitive folly of modern missions.

For some reason, no one has written a best-selling book about the real-life 19th-century missionary John Mackenzie. When white settlers in South Africa threatened to take over the natives' land, Mackenzie helped his friend and political ally Khama III travel to Britain. There, Mackenzie and his colleagues held petition drives, translated for Khama and two other chiefs at political rallies, and even arranged a meeting with Queen Victoria. Ultimately their efforts convinced Britain to enact a land protection agreement. Without it, the nation of Botswana would likely not exist today.

The annals of Western Protestant missions include Nathan Prices, of course. But thanks to a quiet, persistent sociologist named Robert Woodberry, we now know for certain that they include many more John Mackenzies. In fact, the work of missionaries like Mackenzie turns out to be the single largest factor in ensuring the health of nations.

'This Is Why God Made Me'

Fourteen years ago, Woodberry was a graduate student in sociology at the University of North Carolina–Chapel Hill (UNC). The son of J. Dudley Woodberry, a professor of Islamic studies and now a dean emeritus at Fuller Theological Seminary, started studying in UNC's respected PhD program with one of its most influential figures, Christian Smith (now at the University of Notre Dame). But as Woodberry cast about for a fruitful line of research of his own, he grew discontented.