The Rev. Derek Miller has seen the future of the church in America. And it is small. On a Sunday morning in early November, Miller, guitar in hand, stepped up to the microphone at Cornerstone Church of Spring Green and began singing the familiar Charles Wesley hymn "O for a Thousand Tongues to Sing." A handful of people scattered in the sanctuary sang along, including a church elder in the front row next to a pair of young kids tapping on tambourines. By the time all the latecomers had arrived, there were 12 people in the congregation.