Bergman Island sounds, on first acquaintance, like a theme-park attraction. Roll up, roll up! Let us speed you through the shed where Max von Sydow is weeping and then plunge you downwards until you come face to face with a priest struggling with his faith. Then you’ll twist hard left – hold on! – to encounter Liv Ullmann suffering from a series of nightmares in which God appears graceless and indifferent.