This book was a little gem that I discovered shortly after my grandmother passed away in 2003. We were tidying up her house and this book was discovered at the bottom of a suitcase. Assuming that it was simply a comic book, I took it home. What I got was a highly subjective analysis of the popular peanuts comic strip and a search for religious meanings and messages within the Peanuts comics. Apparently, this book was quite a big deal during the 1960s, and (at least according to wikipedia) sold more than ten million copies.
Interestingly, Charles Schulz himself liked the book, though he described himself as a Secular Humourist, rather than belonging to a particular religion. This to me seems more consistent with the comics, which seem to comment more on human nature, rather than making the case for any one religion. If Christianity appears dominant throughout the comics, it is probably more a reflection of American suburban life in the 1960s, rather than an overt religious message. But that is just my own, equally subjective opinion.