I just finished reading Crazy Love by Francis Chan and for me it was the most spiritually convicting book I have read in some time. Chapter four alone -- "Profile of the Lukewarm" really challenged my faith and caused to me to do some serious soul assessment. It is interesting to note that as challenged as I was by the content that was speaking to me, the flow of the book moves rather quickly.
The book is also filled with many other challenging statements throughout. Here are a few that I hope will prod you to read it.
"The greatest knowledge we can ever have is knowing that God treasures us." p. 61
"God's definition of what matters is pretty straightforward. He measures our lives by how we love." p. 93
"When we love, we're free! We don't have to worry about a burdensome load of commands, because when we are loving, we can't sin." p. 102
"We try to set our lives up so everything will be fine even if God doesn't come through." p. 168
"Most of use 'I'm waiting for God to reveal His calling on my life' as a means of avoiding action. Did you hear God calling you to sit in front of the television yesterday?" p. 169