Richard Fletcher gives us a nice little summary of the formative years of Christian/Muslim interaction. And they weren’t pretty. Or simple. I highly recommend this book to anyone interested in understanding the current conflict between Christians and Muslims.
It’s a sibling rivalry, similar in dynamic to the Jewish/Christian relationship. I particularly like Jon Levenson’s book on the Jewish themes of this complicated rivalry. The most fascinating similarity is that Christians in the early years of Islam saw it as just another Christian sect — in much the same way that Judaism saw early Christianity as a Jewish sect.