In “The Christians,” a pastor sees his small church grow into a mega-church, inspiring him to deliver a sermon that shakes up his congregation. The Dallas Theater Center opens the play tonight, and director Joel Ferrell joins us to talk about the play’s theme of how religion can both unite and divide. We’ll also be joined by Mark Wingfield, associate pastor at Wilshire Baptist Church, who consulted on the production. “The Christians” runs through Feb. 19 at the Kalita Humphreys Theater.