I highly recommend Choosing Your Faith by Mark Mittelberg. ( You can learn more about the book by watching Lee Strobel’s interview of Mark.) The author helps readers discover how to choose what to believe; I’ve given this book to two young non-believers.
You may also want to have copies of the Choosing Your Faith New Testament. I have some in our home that I give to people who are interested in knowing Christ. These paperback Bibles are in the easy-to-understand New Living Translation. This New Testament also features several of Mark’s articles about why we believe in order to help readers make a decision about their faith.