Does Richard Wagner's "Parsifal" represent the composer's return to the Christian faith of his youth , or is it a final, anti-Semitic screed from one of the most virulent racists of his time? Lou Santacroce, former host of National Public Radio's "At the Opera" examines the central characters of the opera, the "regeneration" writings that Wagner penned while composing his final work, and the full (and, for some, surprising) history of the Holy Grail legend that forms the basis of what Wagner called, not an opera, but a "stage-consecrating festival play."