The Kitáb-i-Íqán (The Book of Certitude), which was designated by Bahá’u’lláh as the the Lord of Books revealed by the Most Exalted Pen and called by ‘Abdu’l-Bahá the fountainhead of the water of eternal life, is unique in the history of religions and holy scriptures. This book is not only the key for opening the mysteries of the past holy scriptures, but it revolutionizes the concepts of religion, eschatology, and theology by resolving and removing eschatological barriers and establishing the fundamentals of a universal religion and a universal theology that integrates and harmonizes the contending religious ideologies.
Study of the Kitáb-i-Íqán was recommended by Bahá’u’lláh. He said “blessed is the one who had reviewed it and witnessed to its testimony and had studied and pondered its contents.” ‘Abdu’l-Bahá stated “O thou who art seeking after the knowledge of God! Immerse thyself in the ocean of the explanation of the Beauty of the Merciful, so that thou mayest gather from its depths the pearls of the wisdom of God.” Shoghi Effendi stated “The Íqán is the most important book written on the spiritual significance of the Cause. I do not believe any person can consider himself well versed in the teachings unless he has studied it thoroughly.”