I would even recommend this book to non-Christians since the book in fact has an evangelistic edge to it (it even includes a section at the end specifically aimed at a non-Christian).
However, I realised the one I read was a different edition to what is most commonly available nowadays. My copy looks more like the following:
It's published by IVP, and the newer edition is from Crossway. The newer edition does not have the evangelistic message section at the back, and its closing chapter was in fact the preface in the IVP edition. I may have to think twice about the evangelistic value of the newer edition, and may not use it as an evangelistic tool.