Carol Cymbala's ministry in a tough inner-city neighborhood in New York can be summed up in one word: unlikely. She is the director and songwriter for a Grammy Award-winning choir-yet she doesn't read music. She is the pastor's wife in a 6,000-member congregation filled with people of color-and she is white. A shy girl who struggled to get through school, she is the last person you'd expect to stand before a packed house at Radio City Music Hall,...