Rituals and ceremonies are practiced to show dedication and faith to a religion. The connection between religious beliefs and religious ceremonies is that ceremonies serve as the concrete expression of religious belief. Religious beliefs are abstract ideas and therefore require faith. The way in which people express their beliefs and pay honour and respect to them is through rituals and ceremonies.
An idiom is a funny saying/phrase. It does not serve as any criminal law or military action. It doesn't mean a foolish person, but it is just an artistic style used in some texts.
