It is communion Sunday at a mixed-race church. A black pastor and white head elder stand before the sanctuary as lay leaders pass out the host. An African-American woman sings a gospel song as a woman of Asian descent plays the piano. Then a black woman in the congregation throws her hands up and yells, over and over, "Thank you Lawd!" A few other African-Americans in the pews say "Amen," while white parishioners sit stone-faced. The befuddled white...