I had this book in dead tree version and it got misplaced (probably during a move) so I bought a version to read on my tablet. I have read the book through several times. I highly recommend this book to any man looking to better pleasure his wife and to any woman looking to understand her own anatomy better.
No, the author isn't a Christian. However, other than stressing the importance of a woman having an orgasm, I didn't read a lot of philosophy into the book. Yes, the book does tend to use more generic language about who the woman is as opposed to using language like "your wife", but even if that sort of thing bugs you, I recommend powering through it due to how valuable the more scientific aspects of the book's content actually is.
One of the best things about this book is the extended anatomy lesson. Most of us have seen the medical diagrams of a woman's external genitals. Most of us have even seen the medical diagrams of what is down there internally as well. What few of us have been exposed to is the complex network of nerves and how they are structured in that region. A woman's intimate area is a web of nerves and muscles all of which can be leveraged to bring her pleasure. As was said previously, every woman is unique and so there is a required communication element, but once you start to understand the interplay between a woman's vagina, labia, and clitoris, you can gain a whole new appreciation for how complex her physical sexual response can be. I'm pretty enamored with that part of my bride's body, but after reading this book I have a whole new appreciation and fascination with her down there.
Another very valuable aspect of this book is the detailed description of a woman's arousal from initial "yes, let's have sex" all the way through "*pant* *pant* oh wow that was amazing". This description is fairly limited to the biological response, but does talk about what is going on at each phase so you can discern for yourself if your wife needs to linger at various stages and why you might consider helping her linger before you arouse her further. This is especially important if OS is going to be used as a "warm up" for PIV.
Another big value for men in this book is that it strives to free husbands of the illusion set by the porn industry that if you can't make your wife orgasm through penetration, you're no good as a lover. Again, communication is key but for those with a hair trigger, this is an immeasurably freeing realization. Sure, giving her a PIV orgasm gives you a very nice confidence boost, but many women here will confirm that PIV orgasms are extremely elusive if not outright impossible. This book details why for some women their anatomy just isn't configured for PIV orgasms which further makes the case for OS and MS as a way to bring her to climax.
If cunnilingus is part of your sexual repertoire, this book will probably make you better at it. Before reading it, my bride enjoyed me giving her OS, but didn't seem to want it very often. After reading this book, her reactions are much more intense and her orgasms much stronger and she will regularly request it.
I strongly recommend this book to men and women. Reading it on your own can provide some interesting insights. Reading it together can start some very productive conversations. Multiple readings provide a good refresher for the more technical information.