We highly recommend Crazy Love by Francis Chan.

Check out the Crazy Love Book website.  Here is an excerpt:

Does something deep inside your heart long to break free from the status quo? Are you hungry for an authentic faith that addresses the problems of our world with tangible, even radical, solutions? God is calling you to a passionate love relationship with Himself. Because the answer to religious complacency isn’t working harder at a list of do’s and don’ts — it’s falling in love with God. And once you encounter His love, as Francis describes it, you will never be the same.

Because when you’re wildly in love with someone, it changes everything.