I am currently reading my way through a long list of science fiction and fantasy titles. (http://www.npr.org/2011/08/07/138938145/science-fiction-and-fantasy-finalists if you are interested in the list).
Having recently read Zealot, written by a Muslim author about Jesus, I felt it was only fair that I also read The First Muslim by a Jewish author about Mohammed. Now I just need a book about Judaism by a Christian author to complete the hat-trick!
You need to be on the outside looking in if you want to write a unbiased biography of a religious figure. Both books were good and gave me unexpected insights into each religion and sometimes all religions.
I knew next to nothing about the origins of Islam. The First Muslim has educated me about the tenets of that religion and given some insights into the psychology of its followers, in the same way that Zealot gave me new ways to understand both Judaism and Christianity. Suddenly, certain reactions and opinions by religious groups are explained. [Why were Muslims so upset by those Danish cartoons? Why are the Jewish settlers so aggressive about building in Palestinian territory?]
It may be a historical book, but if you want to understand the conflicts of the 21st century, this would be a good starting point.