"What if church wasn't just a building, but thousands of doors?" asks a new website launched by the United Methodist Church. "Each of them opening up to a different concept or experience of church. . . . Would you come?" After watching its membership drop nearly 25 percent in recent decades, the United Methodist Church, which is still the nation's largest mainline Protestant denomination, thinks it knows the answer. So it's pouring $20 million into a new marketing campaign, including the website, television advertisements, even street teams in some cities, to rebrand the church from stale destination to "24-7 experience."...