I was doing some research and I found this entry on Wikipedia
"Jodo Shinshu Buddhism was the original supporter of lower castes. The side-effect of this liberating philosophy, however, was that it led to a series of anti-feudal rebellions, known as the Ikkō-ikki revolts, which seriously threatened the religious and political status-quo. Accordingly, the political powers engineered a situation whereby the Jōdo Shinshū split into two competing branches, the Shinshu Otani-ha and the Honganji-ha. This had the consequence that the sects moved increasingly away from their anti-feudal position towards a feudal one.
Later the state also forced all people to belong to a specific Buddhist school according to the formula: the imperial family is in Tendai, the peerage is in Shingon, the nobility is in Jōdo (Honen's followers), the Samurai is in Zen, the beggar is in Nichiren, and Shin Buddhists (Shinran's followers) are at the bottom."
https://en.wikipedia.org/wiki/Burakumin#Religious_discrimination
This is a repost of a question from u/Apiperofhades.
Edit: not sure who might be downvoting this. Have I offended someone?
Some Wikipedia articles have been carefully rewritten in recent years to reflect current scholarly consensus. This, alas, is not one of them, and I would say that most of what is offered here is simply wrong.
Looking at religion during the Edo/Tokugawa/Early Modern period (roughly 1603-1868), the place to begin is with Christianity, which was tolerated in the early 17th century and then persecuted with increasing exuberance until it was completely outlawed in the 1630s. A Christian rebellion, the Shimabara Uprising of 1637-38, only increased the determination of the state to stamp out underground Christians and to control, as much as possible, religious institutions. The head of each family was thereafter required annually (in theory) to register at a Buddhist temple and to verify that no member of the household was Christian.
Buddhism had divided fortunes during this period, with some schools being coopted by the Tokugawa State and others experiencing widespread popular devotion and massive increases in Buddhist pilgrimage. Religious schools were not limited to specific status populations, as suggested by the quoted Wikipedia article, though of course some schools had stronger associations with certain groups of patrons. Buddhist temples played incredibly complex and diverse roles in the lives of their priests and families, their parishioners and the residents who lived around their complexes. Many Buddhist temple complexes also included Shinto shrines and sponsored syncretic forms of Buddhist-Shinto worship. Some freestanding Shinto institutions were also quite influential, and Shinto experienced a revival of sort among nativist intellectuals.
One of the most ignored religious institutions of this period was the system of Toshogu shrine complex, based at Nikko, which sponsored the worship of Tosho Daigongen (Gongen-sama), the spirit of Tokugawa Ieyasu, across the archipelago.
Meanwhile outside of the system of institutionalized Buddhism and Shinto, new religions and folk religions thrived throughout this period, focusing on various themes: mountain asceticism, yin-yang theory, and faith healing, to give a few examples.
You might look at some of the publications of Barbara Ambros and Nam-lin Hur. Also, a lot of scholarly material in English is available for free online, most importantly the Japanese Journal of Religious Studies:
https://nirc.nanzan-u.ac.jp/en/publications/jjrs/listofjournals/