The Kitáb-i-Íqán (Persian: كتاب ايقان‎‎, Arabic: كتاب الإيقان‎‎ "The Book of Certitude") is one of many books held sacred by followers of the Bahá'í Faith; it is their primary theological work. One Bahá'í scholar states that it can be regarded as the "most influential Quran commentary in Persian outside the Muslim world," because of its international audience.[1] It is sometimes referred to as the Book of Iqan or simply The Iqan.

The work was composed partly in Persian and partly in Arabic by Bahá'u'lláh, the founder of the Bahá'í Faith, in 1861, when he was living as an exile in Baghdad, then in a province of the Ottoman Empire. While Bahá'u'lláh had claimed to have received revelation some ten years earlier in the Síyáh-Chál (lit. black-pit), a dungeon in Tehran, he had not yet openly declared his mission. References to his own station therefore appear only in veiled form. Christopher Buck, author of a major study of the Íqán, has referred to this theme of the book as its "messianic secret," paralleling the same theme in the Gospel of Mark.[2]

The Íqán constitutes the major theological work of Bahá'u'lláh, and hence of the Bahá'í Faith. It is sometimes referred to as the completion of the Persian Bayán. When it was lithographed in Bombay in 1882, it was the first work of Bahá'í scripture to be published.[3] It was first translated into English in 1904, one of the first works of Bahá'u'lláh to appear in English.[4] Shoghi Effendi, who retranslated the work into English in 1931, referred to the work as follows:

A model of Persian prose, of a style at once original, chaste and vigorous, and remarkably lucid, both cogent in argument and matchless in its irresistible eloquence, this Book, setting forth in outline the Grand Redemptive Scheme of God, occupies a position unequalled by any work in the entire range of Bahá'í literature, except the Kitáb-i-Aqdas, Bahá'u'lláh's Most Holy Book

The uncle of the Báb, Ḥájí Mírzá Siyyid Muḥammad, had been perplexed to hear that the promised one of Islam was his own nephew. When he was told that this was the same objection voiced by the uncle of the prophet of Islam, he was shaken and decided to investigate the matter. In 1861 he traveled to Karbila, Iraq, to visit his brother, Ḥájí Mírzá Ḥasan-'Alí, and then went to Baghdad to meet Bahá'u'lláh. There he posed four questions about the signs of the appearance of the promised one in writing to Bahá'u'lláh. The 200 pages (in original languages) of the Kitáb-i-Íqán were written in the course of at most two days and two nights in reply about January 15, 1861.

The book is in two parts: the first part deals with the foundational discourse that divine revelation is progressive and religions are related to one another, with each major monotheistic religion accepting the previous ones and, often in veiled terms, prophesying the advent of the next one. Since the questioner is a Muslim, Bahá'u'lláh uses verses from the Bible to show how a Christian could interpret his own sacred texts in allegorical terms to come to believe in the next dispensation. By extension the same method of interpretation can be used for a Muslim to see the validity of the claims of the Báb. The second and larger part of the book is the substantive discourse and deals with specific proofs, both theological and logical, of the mission of the Báb. One of the best-known and best-loved passages of this part is known as the "Tablet of the True Seeker."

Shoghi Effendi has offered the following lengthy description of the book's content:

Within a compass of two hundred pages it proclaims unequivocally the existence and oneness of a personal God, unknowable, inaccessible, the source of all Revelation, eternal, omniscient, omnipresent and almighty; asserts the relativity of religious truth and the continuity of Divine Revelation; affirms the unity of the Prophets, the universality of their Message, the identity of their fundamental teachings,