Karen Armstrong's "A History of God" is a tremendous resource for those interested in the history of religions in general, and in monotheism in particular. She looks not only in the different religions (Judaism, Christianity, and Islam in particular), but also in the way that man's perception of God changed within each religion over time. Starting with the early history of man and religion, she proceeds right through to religion as of the early 1990's. The book was first published in 1993, so you will not find any references to September 11th or any of the polarizing events that have happened as a result. Instead you will find a much more even look, which is useful in and of itself.
While this book is a tremendous reference, unfortunately it does have a significant weakness as a reference, and that is that the text itself is not all that organized. Her choices for the eleven chapters are fine, but you will find no sections or subsections within the chapters. Instead each chapter is just a long recitation with no breaks, and this can make referring back to a section rather difficult. The book does have a decent index which helps. Also, there is a very good bibliography which also helps with additional research on a topic.
The writing is a little uneven. Some sections are very well done, and others are a bit more difficult to follow, however the writing is never poor. In particular, her discussion of the early history of each of the major monotheistic religions is very well done, and it gives the reader a good understanding of what those religions were like before they started adapting to other forces in the world. The polytheistic origins of Judaism, the lack of divinity in Christ, and the equality of women to men in Islam are just a few of the topics which would undoubtedly shake up those with fundamentalist beliefs.
The only other slight negative I can think of is with regards to some inconsistency in the area of religion today. In her introduction, as well as in the last chapter, she refers to polls which indicate that 99 percent of the people in the U.S. believe in God. She never provides a reference to these polls. The problem is that in that same last chapter `Does God Have a Future?' she discusses the movement of people away from belief in God. These two concepts seem to be at odds with one another, and she never addresses this contradiction. While there may be polls which show such a small number of atheists, the polls that I have seen show that atheists/agnostics make up 8.4% of the population in 1990 and are up to 15.0% of the population in 2000. This data seems to support the rest of her discussion in the chapter better than the polls she mentions.
I would definitely recommend this book to pretty much everybody. It is a window into our past and a tremendous reference for those interested in world history as well as those who are studying religion.