Shinbutsu-shugo (syncretization of Shinto with Buddhism) refers to blending of indigenous belief and Buddhistic faith to reconfigure one belief system. Although it generally refers to the syncretism of Japanese faith in Jingi (gods of heaven and earth) and Buddhism, in a broad sense, it may refer to a syncretism of an indigenous belief and Buddhistic that had happened in various parts of the world as Buddhism was spread. Hereafter, the syncretization of Shinto with Buddhism in Japan is described. It is also known as "Shinbutsu-konko."
Introduction of Buddhism
In 552 (in 538, according to another theory), when Buddhism was officially introduced into Japan, Buddha was recognized as banshin (a deity of a neighboring country) and equivalent to a Japanese deity. According to "Nihonshoki" (Chronicles of Japan), the first Japanese Buddhist priest who entered into priesthood and deified the Buddha was a nun called Zenshin-ni. The nun thought to have deified the Buddha in the same manner as a shrine maiden deified Japanese gods of heaven and earth.
The view that the burning down of a temple may result in the arsonist being cursed by the Buddha is thought to come from the Japanese belief in Jingi, as Buddhism does not accept the concept of curses.
Erection of Jingu-ji Temples (temples associated with shrines)
As Japanese people realized that the Buddha had a nature different from Japanese deities, they began to regard deities and human beings on the same level and thought that like human beings, Japanese deities also wish deliverance for salvation of the Buddha to end suffering. From the beginning of the Nara period, Jingu-ji Temples started to be erected in the national shrines; for example, in 715, a Jingu-ji Temple was erected from an oracle of Kehi-jingu Shrine, Echizen Province. Moreover, Jingu-ji Temples were built within or out of precincts of shrines, such as Kashima-jingu Shrine, Kamo-jingu Shrine and Ise-jingu Shrine, by priest Mangan, et al. Furthermore, bodhisattva-like statues were made as shintai (an object of worship housed in a Shinto shrine and believed to contain the spirit of a deity), known as Sogyo Hachimanshin, in Usa-jingu Shrine, etc. In the late Nara period, erections of Jingu-ji Temples were widely seen even at rural shrines; Tado Ogami (great god) who was a guardian deity of a local ruling family in Kuwana County, Ise Province, wished to practice of Buddhist teachings, in a oracle, giving up the title of deity. From the late eighth century to the early ninth century, deities in various provinces, such as Wakasahiko Ogami, Wakasa Province and Okitsushima Ogami, Omi Province, began to show willingness to embrace Buddhism. In this way, in order to relieve an agonized deity, a temple was built by the side of a shrine, and it was called Jingu-ji Temple. Moreover, sutra was chanted before Shinto altar.
Such oracles of deities embracing Buddhism were thought to be a wish of powerful local ruling families who enshrined the shrines. As the social structure changed by introducing the system of the ritsuryo legal codes, local ruling families, who were simply the head of a community, became like feudal-lords with private property, and the conventional Jingi belief supported the religious service by a community was in a deadlock. The local ruling family started to become aware of the guilt owing private property and sought a new personal emotional prop. The reason Mahayana Buddhism became popular among local ruling families might be that it taught that sin was forgiven through Ritako (Altruistic Practice). Yugyo-so (traveling monk) who learned Zo-mitsu (the Mixed Esoteric Buddhism) thought to appear to meet their demands and encourage building Jingu-ji Temple. Although Esoteric Buddhism had not been systematized yet, it might be easy to blend with the Jingi belief because of its magical practice and teachings, focusing on miracles, and affirming accumulation and the prosperity of secular wealth. It might be also easy to be accepted by people under the local ruling family.
While shrines came close to temples, temples also came close to shrines. In the late eighth century, temples recognized a deity that was related to them as their guardian deity or tutelary shrine. The relationship between Kofuku-ji Temple and Kasugataisha Shrine in 710 was the oldest example. Moreover, Todai-ji Temple made a branch shrine for deity of Usahachiman-shin, which helped erecting the Great Buddha. The shrine is called Tamukeyama Hachimangu Shrine at present. As for other influential temples in the ancient times, Enryaku-ji Temple had Hiyoshi-taisha Shrine, Kongobu-ji Temple had Niutsuhime-jinja Shrine, and To-ji Temple had Fushimi Inari-taisha Shrine, as their guardian shrines.
In this phase, although deities and the Buddha were under the same belief system, they were recognized as a different existence; they were not yet considered same existence. The phase may be called Shinbutsu-konko to differentiate from later Shinbutsu-shugo. Jingu-ji Temples were built in many shrines, and shrines were built in temples. It compensated Jingi belief and Buddhism, without oppressing the conventional Jingi belief.
Systematization by Mahayana Esoteric Buddhism
Such Jingu-ji Temples were led by the Zo-mitsu Buddhist scripture and tried to settle with the support of the local ruling families. On the other hand, this situation might have accelerated the separation of Jingi belief from local ruling families. There was a concern that it might affect collection of the Soyocho (a tax system, corvee), which was thought be derived from first-crop-offering ritual of Jingi belief, and the centripetal force of the country through Jingi belief. On the other hand, as the system of the ritsuryo legal codes changed, major temples and shrines had started to aim at territorial expansion while local Jingu-ji Temples had begun to desire to be approved as a branch temple of main temples.
The Imperial-Court promoted the movement to keep centripetal force of Jingu-ji Temples in various countries by joining Jingu-ji Temples to the main temples that were under national protection. However, Kukai's Shingon sect of Buddhism attracted Jingu-ji Temples of various countries as a central large temple because it had magical essence, which was easy to combine with Jingi belief, as well as preaching a story, providing protection for the nation, universality, and abstractness. Moreover, to meet the demand, esoteric Buddhism was also progressively accepted by Ennin and Enchin in the Tendai-shu sect.
On the other hand, Shugendo (mountain asceticism-shamanism), which had developed from the Nara period, was also strongly influenced by the esoteric Buddhism of both sects and was evolving independently.
Worship of vindictive spirits
On the other hand, prosperity of such esoteric Buddhism brought relativization of sovereignty. At the same time, expansion of the Fujiwara clan's influence ruined former prestigious families. Under such circumstances, worshiping vindictive spirits became popular to justify the discontent and repulsion to sovereignty by using the name of deceased, who lost in a political strife.
This trend led to the epidemic of the goryoe (ritual ceremony to repose of spirits of a deceased person) in the ninth century. One may see it as an example of shinbutsu-shugo since ritual for repose of souls, based on esoteric Buddhism, was carried out in addition to the custom of vindictive spirit festival based on traditional Jingi belief. Especially, when the vindictive spirit of SUGAWARA no Michizane turned to Tenjin belief, he was regarded as Tenbu (deities who reside in a heavenly realm, one of six realms in which the souls of living beings transmigrate from one to another) according to Buddhistic logic. Therefore, it is shown that esoteric Buddhism influenced the view of curses to sovereignty.
The typical example is seen at TAIRA no Masakado's accession to the throne. At the enthronement of new emperor Masakado, it supposed that Hachiman (God of War), deity of shinbutsu-shugo and Imperial Family's soshin (ancestor honored as god), granted the throne, SUGAWARA no Michizane wrote the Iki (court rank diploma), and a shrine maiden of Jingi belief had an oracle to play Buddhistic music at the ceremony. The influence of Buddhism, as a means to justify the logic of sovereignty relativization, is strongly seen.
Logic of "muck" evasion
Thus, the Jingi belief started to arm with reasoning to confront Buddhism, which spread to the public who demanded magical belief.
The view of bipolar confrontation between purity and muck, which had not been very notable formerly for Jingi belief, developed and was emphasized. Accordingly, the way of muck removal had been changed; it is confirmed that from the ninth century to the tenth century, purificatory asceticism was mainly applied, under the influence of Onmyodo (way of Yin and Yang; occult divination system based on the Taoist theory of the five elements), instead of former purification.
Because of the consolidation of the logicalness, Jingi belief was able to confront the invasion of Buddhism and symbioses with. The influence of muck idea was seen in Jodo (Pure Land) sect at the end of the tenth century. For example, "Ojoyoshu" (The Essentials of Salvation) describes a logic employing muck of Jingi belief to explain Buddhism's own pure and impure thought.
Honji-suijaku setsu (theory of original reality and manifested traces)
However, the spread of Pure Land Buddhism showed the predominance of Buddhism, which could present the way to fundamentally flee from muck, while Jingi belief could only evade muck. According to Honji-suijaku setsu, Buddha and bodhisattvas are honji (original ground or true nature), and they come to this world, in the shape (suijaku - literally, trace manifestation) in accordance with the life to be saved. It may be understood that Buddhism tried to take in Jingi belief while Buddhism was considered superior. The harmonization of Shintoism and Buddhism might be theoretically supported by assuming that Buddha and bodhisattvas were the absolute beings, while deities were their incarnations.
Moreover, such a view of Buddhism predominance touched the hearts of samurai, who were commonly close to muck, and led to prosperity of future Hachimanshin and Tenjin beliefs.
Furthermore, during the Kamakura period, it became popular to make explanations, according to esoteric Buddhism, of Ryobu Shinto based on Honji-suijaku setsu, Oharae no Kotoba based on Sanno Shinto and the enshrined deities of deities and shrines appeared in Kiki-shinwa (the Kojiki, Nihonshoki and mythology). The phenomenon is so-called chusei Nihongi (medieval Nihongi).
Historically, Buddhism had connoted local deities not only in Japan but also in India and China; the gods of the Buddhistic Tenbu were originally the deities of Hinduism. Such nature of Buddhism was the key factor of the birth of shinbutsu-shugo.
From the end of the Kamakura period to the Period of the Northern and Southern Courts (Japan), Ise Shintoism and Yoshida Shintoism appeared; they advanced the Shinponbutsujaku setsu, insisting that their deity was honji while the Buddha was an incarnation, objecting to the Buddhist priests' Shintoism view. During the Edo period, Suika Shinto, which integrated both schools with the theory of Neo-Confucianism, appeared. They served as doctrine of the mainstream faction of Jingi belief, and contributed to the doctrine establishment of Shintoism.
However, shinbutsu-shugo thought itself undiminished until the "separation of Buddhism and Shintoism" during the Meiji period. It has also influenced the mentality of Japanese in modern times and the present day.