This is a neat little book.
After reading Mere Christianity, I kind of got on a Christian literature kick, and finally picked up a book that had been recommended to me many times by various friends. After finishing it, I wondered why I hadn't read it earlier. This little book is a gem. Only 160 pages, but those pages are packed with very helpful information. He explains the atonement and the "good news" of Christ's gospel in a way that is so simple and accessible—that is, for such a complicated topic.
What Robinson really explores is this: As Christians, we believe in Christ, but do we really believe Him? Do we believe that Christ can make us perfect? That He can save us? That His sacrifice was for each one of us? Though this is clearly a central principle of the gospel, a lot of people still struggle to believe that Christ would actually do this for them. But the good news is—he did.
If you haven't read it yet, you need to. You won't regret it.