“The Historical Dictionary of the Bahai Faith” is a somewhat problematic mini-encyclopedia of Bahai, a new religious movement originating in Persia (Iran) during the 19th century. Bahai is at bottom a modernist form of Shia Islam, recast as a non-Islamic religion. However, you are unlikely to learn this from this book, since it's written by true believers in the faith. While this isn't necessarily “wrong”, it does give a curious impression – imagine a historical dictionary of Communism written by Communists, or of the Jehovah's Witnesses written by JWs working for the Brooklyn Watchtower.
The dictionary contains relatively little information on the so-called Central Figures of the Bahai faith (Bab, Bahaullah and Abdul-Baha) and their successor, the Guardian Shoghi Effendi. The editors also admit that many “Oriental heroes” of Bahai have been excluded, giving the dictionary a somewhat Western slant. Most of the entries seem to be about Bahai missionaries and leadership figures. Thus, we learn that Kamil Abbas-Rida from Iraq worked as a missionary on the Seychelles and that he was imprisoned by the Iraqi Baath regime from 1973 to 1980. Agnes Baldwin Alexander from Hawaii was a prominent world-wide missionary, preached the faith to the Chinese leader Sun Yat-sen and supported Esperanto. Holmfridur Arnadottír was the first and only Bahai on Iceland during her lifetime. And so on!
The dictionary also contains short entries on Bahai religious concepts such as the Abha Kingdom, the Bahai view of the resurrection, or the holy day known as the Ascension of Abdul-Baha. More disturbingly, we learn that Bahais are strictly forbidden to socialize with defectors from their faith. These are known as Covenant Breakers, are said to have ego issues and are to be consistently shunned, lest their spiritual infestations affect the faithful. In plain English: Bahai is a cult. Which I suspected already before picking up this little volume!
I don't think you can really learn that much about the Bahai faith itself from this book, but I suppose it might be a good reference for people who for whatever reason decide to become Bahai-watchers…