"Global Christianity in the Modern World" is the theme of Wheaton College's McManis Lectures for 2001. It's a fitting theme for the beginning of a century in which the map of faith is sure to undergo massive revision.

Yesterday's McManis lecturer was Grant Wacker of Duke Divinity School, one of our finest historians of American religion, speaking on "The Waning of the Missionary Impulse: The Case of Pearl S. Buck." The story Wacker told is a fascinating one. Buck (1892-1973) was a woman of extraordinary energy and accomplishment, generous and tireless in doing good works, organizing, protesting—all the while managing a large family of adopted children. The first American woman to win the Nobel Prize in Literature, she wrote books that were read around the world; her novel The Good Earth sold more than four million copies, and her influence was immense. Wacker quoted biographer Peter Conn: "For two generations of Americans, Buck invented China."

For evangelical Christians, Buck's story is also sorrowful. The daughter of missionaries, raised in China, Buck herself was full of evangelical fervor in her youth (as her letters make clear), though she later tried to rewrite that part of her life, embarrassed by the reality. Sometime in her early twenties she began to feel increasingly sympathetic to China as it was, and increasingly critical of the missionaries bent on saving it. By the time of her 1932 speech, "Is There a Case for Foreign Missions?", which created a great stir, she had given up Christian faith.

It is easy to see in Buck's case the arc of mainline Protestantism worked out in a single life. But Wacker drew attention to nuances that prompt us to look more deeply. First, while not pretending to "explain" Buck's ...