This book explores personal beliefs that individuals and groups maintain, in spite of lack of objective evidence to support those beliefs. The idea for the book originated from the author's personal interest in Dowsing, a mystic form of searching the earth for ground water and other items that may lie beneath the surface of the ground. This interest expanded into other "unnecessary beliefs" people may hold. As a result, the author chose the title "Shibboleth" which means a word or custom that differentiates people in a group from people not in that group, often resulting in value judgments about contrasting beliefs. The book explores various beliefs people may hold about mysticism, religion, superstitions, mythologies, politics and related topics. For the most part the author presents a balanced unbiased discussion of the various topics, but on the subject of Dowsing, the reader may detect a slight predisposition to the topic.