Why did the Mononobe and Nakatomi clans oppose Buddhism?

During the 6th and 7th centuries, the Mononobe and Nakatomi clans opposed the introduction of Buddhism primarily because it threatened their traditional influence and status within the Japanese court.12

The Nakatomi clan served as the hereditary masters of religious ritual, while the Mononobe clan functioned as warriors. Both clans held significant power under the existing social and religious order. In contrast, the Soga clan championed Buddhism, believing that adopting this new religious system would diminish the authority of the established great clans and consolidate power under the imperial family, with whom the Soga were closely linked through marriage.21

The tension escalated into open conflict when an epidemic broke out; the Mononobe and Nakatomi clans blamed the presence of a Buddhist icon in a Soga-built chapel for the disease. This religious and political strife culminated in a decisive battle in 587, where the Soga family militarily defeated the Mononobe clan, effectively clearing the path for Buddhism to become established as a state religion.12