Korean Messiah: Kim Il Sung and the Christian Roots of North Korea’s Personality CultBy Jonathan ChengKnopf, 768 pages, $36In 1946, a young Korean nationalist named Kim Il Sung stepped onto the stage at the First Congress of the Korean Workers’ Party, held in the immediate aftermath of liberation from Japanese colonial rule. It was likely the first time many Koreans caught sight of the former guerrilla fighter, who would go on to lead the Democr…