From an article in the New York Times, I've just learned about performance artist and activist Bill Talen, who goes by the name Reverend Billy. Dressed for the part and sounding just like a gospel preacher, Talen is often backed by a rousing gospel choir as he preaches against the evils of corporate commercialism and rampant consumerism. They go at their subject with passion and with humor.
website describes it this way: 'We are a post religious church. We hold “services” wherever we can, in concert halls, theaters, churches, community centers, forests, fields, parking lots, mall atriums, and perhaps most importantly, inside stores, as close to the cash register as we can get, within spitting distance of the point of purchase."