This interview with Mr. Dunbar, a member of the Universal House of Justice, gives insights into the importance of studying this divine book.
"....I think it is hard for any of us to define a position for such an exalted book but we can take hints from the marvellous statements of Shoghi Effendi about it, which really are the things that awoke me to the significance of the book -- to the feeling that I had to do a careful study of it. Of course, I had read it early on as a Bahá'í -- I had read it in my pioneer years -- but the "point of departure", if you will, for this endeavour, was a quotation that I found in a letter of the Guardian to one of the friends in California, where he writes that the friends who want to become competent and useful teachers of the Cause should consider it to be their first duty to acquaint themselves as thoroughly as they can with each and every detail contained in the Kitáb-i-Íqán so that, he concludes, "they may be able to present the message in a befitting manner". "...befitting manner..."? "...each and every detail..."? My goodness, I thought to myself, I am going to have to get into this book in a big way!"
"It has been interesting for me to observe the diversity of people that The Book of Certitude has attracted and confirmed to the Cause -- on the different continents of the world, in different periods of Bahá'í development. The Kitáb-i-Íqán has a dynamic that is always there and not something that a believer will want to miss out on! And it provides us with the tools to assist in the Blessed Beauty's project of reconciling the followers of past religions into a single vision -- bringing them to that position of unity that is the consummation of all of the work of all of the Prophets of the past. The Kitáb-i-Íqán gives us insights into the Sacred Scriptures of the past -- the way Bahá'u'lláh quotes them, the significances he implies to the different symbolic terms that are there -- that are crucial to teaching the Faith or learning about the Faith from a different religious background. Then, beyond the significance of the contents of the book in teaching, Shoghi Effendi mentions how the book holds several examples of teaching by Bahá'u'lláh -- indeed the whole book is a study in how to teach, being addressed to a non-believer. The whole nature of the Kitáb-i-Íqán resounds with the attitude that one must have in teaching."
The full text of this interesting interview of Mr. Dunbar is found here.