Bali is volcanic. It is still active.
The Balinese Hindu religion has been amalgamated with many of their older traditions. Placating the gods and driving out evil spirits is part of their culture. There are offering everywhere.
The volcanic soil is very fertile but living on the slopes of an active volcano is a little scary. In order to placate the god of the volcano they built a big impressive temple complex and hold many ceremonies.
We arrived in the middle of one.
It seemed to work. While the volcano did produce some smoke it did not erupt and kill everyone.