The God Debates: A 21st Century Guide For Atheists and Believers (and Everyone in Between) is a clear, accessible, up-to-date account of philosophical wrangles about the existence of God. Though Shook spends much of the book alluding to theology, most of the text actually relates to traditional arguments from Christian apologetics and analytic philosophy of religion. Shook reorganises the arguments in an interesting way, but he covers all the familiar ones, such as versions of the ontological, cosmological, teleological, and moral arguments. To his credit, he takes on more esoteric arguments such as the claim that we must presuppose the existence of God if we are to engage in reasoning and scientific inquiry.
The book is packaged as if it took a neutral stance, but the general direction is clearly one of scepticism towards religious arguments. While Shook introduces a wide range of arguments from various kinds of philosophers and theologians, he ultimately finds all the theistic arguments unpersuasive, and shows (unsurprisingly when you know his background) a strong leaning to atheism and philosophical naturalism. Along the way, however, he gives the religious arguments a pretty good run, and is certainly more comprehensive than most in dealing with their variants.
As a relatively short and introductory book, The God Debates sometimes seems to sacrifice depth in exchange for breadth of coverage. I imagine that people who are deeply immersed in various aspects of these arguments will find a certain thinness and imprecision to some of the discussions. In my own case, I was especially interested in moral arguments for the existence of God, which Shook does actually cover well over quite a few pages. All the same, the book could have done with a more rigorous discussion of what is meant by "objective" morality, "absolute" morality, "relativism", and so on. Although it introduces definitions for all these terms, so it is not likely to mislead anyone significantly, they are used in somewhat non-standard and imprecise senses.
For example, Shook introduces a notion of "cultural objectivity", by which he simply means that certain culture-based moral norms really do (objectively) exist. That, however, is not what people who make out forms of the "moral argument" really want, at least not typically, and arguably it's not what the ordinary, non-philosophical folk want either. Part of the trouble is that what is wanted may be something rather inchoate and poorly understood, some kind of "objective" or inescapable bindingness that transcends social norms, desires, or whatever we, individually or collectively, might actually value. Shook uses the word "absolute" to cover this, and denies that any moral requirements are absolute in this sense. On that I agree with him, but the trouble is that the word "absolute" is often used in moral philosophy with a different meaning - applying to contextually inflexible moral rules such as "Don't lie!"
Absolutism in this latter sense may be contrasted with substantive moral positions (usually consequentialist ones) that tell us that, for example, that whether or not it is wrong to lie will depend on the circumstances. The relevant circumstances will be not so much whether our society has a rule against lying as whether, in a particular context, telling a lie will have good or bad consequences or other characteristics that are supposed to be more important than such surface-level rules that could be taught easily to children.
As a substantive moral position, an absolutism of moral rules such as "Don't lie!" - a crude kind of deontological position - strikes me, and probably most people these days, as highly implausible. But what about the idea that there are moral requirements that are "absolutely" or objectively inescapable? That seems to me to be a mirage, and Shook appears to agree. Terminology aside, though, he does a pretty good of explaining why it's a mirage. Perhaps more could be said as to why we don't need these absolutely and/or objectively inescapable moral requirements. In my experience, this is a difficult concept to explain even to hardened atheists and naturalists, and it would have been useful if Shook, who is very lucid, had had more of a go at it.
It may be that problems like this don't seriously undermine the book's argument, but even slightly more discussion of such points would have beefed up its credibility and usefulness.
The last chapters, where Shook does actually discuss some theology, are fascinating, and I was particularly taken by the very last one, where he identifies a total of twelve (!) worldviews that are on offer in current societies. Even these could be sub-divided because, for example, Shook does not distinguish between Christianity and Islam. He is more concerned to distinguish between, say, Evangelical Fundamentalism of any kind (a form of religion that sees its holy book as genuine revelation, rejects contrary conclusions derived from reason, and shows hostility toward rival worldviews) and Liberal Modernism. Although Shook discusses Evangelical Fundamentalism in Christian terms, there could be versions of religions other than Christianity that meet his description of this worldview. The same applies to Liberal Modernism - there could be Christian, Muslim, Jewish, Hindu, etc., forms of this.
People come with many ways of looking at the world, distinguishable in a number of important dimensions. I doubt that Shook's particular taxonomy, or any such taxonomy can capture everything that's important. Nonetheless, these sorts of taxonomies can be illuminating, often bringing out distinctions that we are inclined to ignore in everyday thinking, where we are often tempted reach for binary oppositions or other very simple schemes. Shook has done us a service with his scheme, in which he tries for some nuanced distinctions not only between different types of religion but also between different kinds of philosophical naturalist positions. This chapter alone is enough to provoke a lot of thought.
In all, this is a lucid, concise, up-to-date, yet comprehensive account of intellectual debates about the existence of God. It is easy enough to be used by senior high school students, and could certainly be useful in undergraduate courses in philosophy of religion. It's not the be-all-end-all of the subject, has its thinner passages, and should not be cited as an unchallengeable authority. But again ... The God Debates is an accessible, thoughtful, cogent book. Shook has filled an important gap.