Here's a link to a couple of books that are currently free:
The Gospel of Ruth: Loving God Enough to Break the Rules by Carolyn Custis James (Zondervan)
Now, the book I'm about to give you a link to should come with a disclaimer. From the title, I'm pretty sure that this book will not go on my list of those I recommend. It sounds like something encouraging minimal faith, which sounds opposite of being sold out for Christ. But it's free, so if you're looking for something to get you thinking about whether the author is on target or not, this one might get you: What's the Least I Can Believe and Still Be a Christian? by Martin Thielen.