"The Book of Certitude gives a sweeping overview of religious truth, explains the underlying unity of the world’s religions; describes the universality of the revelations humankind has received from the Prophets of God; illuminates their fundamental teachings, and elucidates allegorical passages from the New Testament and the Koran. It is, in the words of its translator, Shoghi Effendi, “the most important book written on the spiritual significance” of the Bahá’í Faith."