Liberal Christian book?

I've been thinking about how I would explain my faith to someone. If a Unitarian came to me who was non-Christian or even quite anti-Chrisitan and asked me about my faith as a Unitarian that follows Jesus, I'm wondering what book I could point them to.

I would like there to be a book that was a very simple introduction to Christianity, like a confirmation book, but one that was a liberal and somewhat Unitarian. An inspirational little book about simply following Jesus and loving God, not about believing in a number of strange old doctrines.

I don't want anything like John Spong that spends a good amount of time slagging off conservative Christianity. I want a simple introduction to a liberal Christian faith, from the point of view of someone coming from no Christian background.

I've just felt like I needed to refer to a book like that in conversations I've had to better articulate what I stand for.

Any ideas anyone? Please leave comments.