This book does shake up your beliefs, mostly when there's an investigation on the account of the historical Jesus. At least it did shake my beliefs, when you compare Jesus of Nazareth to Jesus the Christ.
According to the author, he was no more than a man, although quite an appreciable one.
Reza Aslan is Muslim, however, and I'm pretty sure he's taking a leap of faith on that one, because Islam is easy to disprove. Possibly just because it's the faith he grew up with.
As much as researching the historical Jesus makes my faith more of a faith-based leap instead of one based on reason, I still consider myself a Christian. It's more about taking a huge leap of faith and believing the Gospels, just like with any other religion.