The Oprah Winfrey Network is the latest to get into the original scripted series game in these boom times of TV: The network is betting big on Greenleaf, a juicy hour-long drama about a Memphis mega-church and the dynastic family that runs it. With excellent performances, a meaty hook, and an unfamiliar setting, Greenleaf — which premieres tonight, and has already been renewed for a second season — is a rare series that nimbly tackles religious belief.