AT LEAST 25 Christian music festivals are held each summer in America, but they have never catered for theological liberals. Until this year, that is, when the Wild Goose Festival—named after a Celtic symbol for the Holy Spirit—kicked off on June 23rd on 72 wooded acres in eastern North Carolina, not so far from the intellectual hub of Raleigh-Durham. The idea, seven years in the making, was based on Britain’s Greenbelt Festival in Cheltenham, which draws 20,000 people a year. About 1,500 people came to the American version, which explicitly pitched its appeal to artists and musicians, nonconformists, post-Christians, non-Christians,...