From the beginning of Shintoism in the 6th century CE until now, the belief was greatly altered due to the many ingredients added to the religion. Shintoism was the only religion in Japan until Buddhism spread into it in the 6th century CE. Shrines of Shintoism became Buddhist temples. Shinto faiths and traditions took on Buddhist elements and later on, Confucius elements. Lacking complex intellectual doctrines, Shinto had a disadvantage against Buddhism and Confucianism. Shinto accepts all religions and you can be both Buddhist and Shinto.