Hardcover
As a free-thinking believer (in other words, I believe in the gospel of Christ but NOT in the extra rules of every church I've ever known), I've always respected Lewis as a kindred spirit. In this book, he strives to define Christianity in the most basic of terms, without the denomination-specific stuff that doesn't have eternal consequence.
I was surprised to find that I did not agree with Lewis on every point, and even more surprised to realize how much this bothered me. I almost stumbled into my old childish habit of talking myself out of what I know to be true simply because someone with more clout said something different...but I quickly got over that. What I realized was that "mere Christianity" can be summarized in a few words: believe in the Lord, love God, love others. An entire book is going to contain much more than that and is, by its very size, going to tip into the "overexplained Christianity" territory.
There is certainly value to what's in this book and it's clear that Lewis wrote it with pure intent, but remembering that this is not scripture but a man's honest attempt to work out his salvation on paper is absolutely necessary.
B+
Non-fiction #3