Flannery O’Connor, the 20th-century writer who is the subject of the new movie “Wildcat,” is at a dinner party. Sitting around the table with eight, mostly Protestant, writers, the topic of the Mass comes up. One of the men asserts that the Eucharist is simply symbolic, which is a Protestant dogma. Wiry, thin-framed O’Connor perks up as if she is about to lunge at him across the table like a wildcat and says defiantly, “Well, if it’s just a symbol, to hell with it.” Everyone at the table becomes quiet and she realizes how uncomfortable she made them feel and gets up and walks away by herself. …