Russell Moore's baptism in 1983 was a decorous occasion, or at least as decorous as possible when the main event consists of being plunged underwater in front of one’s entire church. The ceremony took place in a formal baptistery inside his family's Mississippi church, with a painting of the Jordan River -- where Jesus was baptized by John the Baptist -- behind the tank. An organ played softly in the background. Mr. Moore wore a long white robe. But a few weeks ago, when it came time to baptize Mr. Moore's 14-year-old son, Jonah, the scene was very different. Jonah wore a T-shirt. Mr. Moore wore sneakers. A full rock band, including drums and an electric guitar, accompanied. And Mr. Moore, who is the public theologian at Christianity Today magazine, submerged his son in a galvanized steel livestock trough hauled onstage at the church just for the occasion.