Ryōbu Shinto is a syncretic mix of Shinto and Buddhism that emerged in Japan during the 8th century. It combines the indigenous beliefs and practices of Shinto with the philosophical and ritual elements of Buddhism. The term "ryōbu" means "two aspects" or "two teachings," referring to the two main traditions that are integrated in this belief system.

The main belief of Ryōbu Shinto is the concept of dualism, which sees the world as being composed of two opposing forces - the material and the spiritual. This dualistic view is influenced by the Buddhist concept of "two truths," which holds that there are both ultimate and relative realities. In Ryōbu Shinto, the ultimate reality is represented by the spiritual world, while the relative reality is represented by the material world.

Another central belief of Ryōbu Shinto is the idea of interdependence and interconnectedness. This is derived from the Buddhist concept of dependent origination, which states that all things are interconnected and dependent on each other. In Ryōbu Shinto, this is seen as the relationship between the spiritual and material worlds, where the spiritual world influences and guides the material world.

Ryōbu Shinto also emphasizes the importance of ritual and purification. This is influenced by both Shinto and Buddhist practices, as both traditions place great emphasis on ritual and purification as a means of connecting with the divine. In Ryōbu Shinto, rituals are seen as a way to purify oneself and attain spiritual enlightenment.

The concept of kami, or spirits, is also an important belief in Ryōbu Shinto. In Shinto, kami are seen as the divine spirits that inhabit all things in nature, while in Buddhism, they are seen as manifestations of the Buddha. In Ryōbu Shinto, kami are seen as both the spirits of nature and the manifestations of the Buddha, further emphasizing the syncretic nature of this belief system.

Additionally, Ryōbu Shinto places great importance on ancestor worship and the veneration of deceased ancestors. This is influenced by both Shinto and Buddhist beliefs, as both traditions place importance on honoring and remembering ancestors. In Ryōbu Shinto, ancestors are seen as guides and protectors, and rituals are performed to honor and appease them.

In summary, the main beliefs of Ryōbu Shinto revolve around the concepts of dualism, interdependence, ritual, purification, kami, and ancestor worship. This syncretic belief system combines elements from both Shinto and Buddhism, creating a unique and complex worldview that continues to influence Japanese culture and spirituality to this day.