I love history but the past couple of years (a decade) have been spent concentrating on only one history: Russia/USSR. Since I'm no longer in school, I thought I'd broaden my horizons. I picked up Karen Armstrong's Islam: A short history at the library and I would highly recommend it for anyone who knows nothing about Islam.
The book is very simplistic and very basic, but it covers all the major points. Armstrong can be condescending at times, but to the readers, not religion. She is a "scholar of religion" (as the dust jacket puts it) and has written many other books about world religion. But she tends to take major issues with those who "corrupt" the original religious beliefs, especially when it's towards a more patriarchal line. Aside from occasional comments about these corruptions, the book does a great job to explain the basic tenants of the religion and its history.
Besides the narrative of book, there are several other reasons I would recommend this book for anyone wanting to know more about Islam. First, there is a great time-line at the front of the book. Second, there is a list of key figures of Islam. Third, there is a glossary of Arabic terms. Fourth, a section containing suggested further reading. Finally, and probably most importantly, the book was written before 2001. Therefore, even though Armstrong does talk about fundamentalist, it is not the focus of the book.
I feel that I could now have an intelligent conversation concerning the religion/history of Islam, although not a very detailed one. However, I now understand the difference between Sunni and Shiia. This distinction seemed important to me considering the amount of space it is currently taking up in the media. Overall the book was a fast and easy read while hitting upon the major points of importance concerning Islam. I really think anyone who opens their mouth to discuss what Muslims believe and why their history points towards terrorism should be forced to read this book. A little understanding could go a long way.