Robert Spencer has made a career of attempting to get his readers to understand the ins and outs of Islam and its practitioners. In this book, as the title aptly describes, he sets out to explain how Muslims view those who do not share their faith. As with his other work he uses actual verses from the Koran to explain what the book sets out as instructions to its adherents.
Spencer uses verses of the Bible to contrast with those in the Koran. He tries to explain the difference between the theoretical assertions of moderate Muslims and their supporters and the actual text. He makes a point of taking politicians and commentators from all political persuasions to task over their assertions and "what Muslims believe"/"what the Koran says". In many cases the text directly contradicts what we have been told by our political leaders.
Barring your spending years learning Arabic and reading the original Arabic text yourself, this is a very good primer in what the Koran says about "kufar" or we infidels. Reading an English translation of the Koran does not really count, as technically speaking only Arabic is the proper language for the text as per the instructions in the text itself.
Now many will and have criticized Spencer for his examination of the Islam and those who practice the religion. There will be those that claim he is attempting to spread unwarranted fear of Islam. With chapter titles like "The Muslim's Worst Enemies: The Koran on Jews," "The Koran on Christians: They're Not So Hot Either" and "'Love your enemies' and other things the Koran doesn't say," you might think they have a legitimate grievance.
Some have even gone as far as to issue death threats against the man for his writing. He makes a clear effort to demonstrate where certain beliefs of the Koran's meaning are put into action.
The style is very simple and easy to read. Spencer has honed his craft and has written a comprehensive book that gives unbelievers the facts on what the Koran says about them.