This study traces the development of orthodoxy in the Jodo Shinshu during its formative period between the twelfth and fifteenth centuries, and examines what impact questions of heresy, both within and outside the Shinshu, had on its early history. The Shinshu has long been one of the largest and most influential schools of Buddhism in Japan. It derived its strength from the great number of common people drawn to its simple doctrine of salvation through faith. The emergence of the Shinshu as a major school of Japanese Buddhism was largely the work of Shinran (1173-1262), the originator of its religious tenets, and Rennyo (1415-99), his tenth generation descendant who oversaw its rise to prominence. Shinran's teachings diverged profoundly from Japan's Buddhist tradition. Specifically, he denied that people in the present age can achieve salvation through personal religious exertions. Instead, he advocated faith or total reliance on the Buddha Amida. Moved by these convictions, Shinran abandoned the longstanding Buddhist custom of clerical celibacy, and thus paved the way for married clergy in the Shinshu. These divergences made his teachings susceptible to misinterpretation and to accusations of heresy.After Shinran's death his followers strove to defend themselves against criticism and to preserve his ideas from distortion. As the Shinshu expanded, deviations inevitably arose, some diluting Shinran's provocative message and others exaggerating it. Hence, the Shinshu found itself assailed from the outside as heretical and divided within by disparate interpretations. The Honganji, a temple built at Shinran's grave site, gradually emerged as the foremost defender of his teachings, with Shinran's descendants serving as its head priest. Though Honganji leaders were not immediately successful in unifying Shinshu adherents, they finally managed to do so during the tenure of Rennyo. He recast Shinran's ideas into a popular religious idiom, he disputed interpretations which he con- sidered inimical to Shinran's thought, and he fashioned the Shinshu into a socially viable religious movement replete with creed, ritual, and sectarian organization. For all intents and purposes, Rennyo was the one who instituted Shinshu orthodoxy. In his wake the Shinshu burgeoned into the largest school of Buddhism in Japan.
