Generally speaking, one can divide religious critique into two categories. The first is to attack religion as a political institution, whereby the social effects of religion are examined and subject to scrutiny. The second is to go after the truth status of religious claims. While these two categories have some overlap, it's worth remembering that truth and utility aren't the same thing.
It is unfortunate that critiques of the utility of religion are taken as the reason for critiques on the truth of religion. It's not that God is a nonsense notion, it's that atheists have some psychological hatred of theism as it is practised that leads to the denial of God altogether. It's unfortunate because the critiques of belief itself are ignored as some outcome of one's impression on the utility of religion, they remain largely unaddressed. Explain the "reasons" for atheism and explain away the need to address atheism.
Herman Philipse's book completely focuses on the second category. This category is further narrowed by the distinction between natural theology and revealed theology, where the focus was almost exclusively on natural theology. The question the book explores is what to make of a concept like God in light of modern science, and is largely an exploration of the case made by the philosopher Richard Swinburne.
To understand the way Philipse laid out the critique, it's worth exploring the three dilemmas Philipse proposes the theist has to answer:
Claims about God's existence are (a) factual claims, or (b) non-factual claims.
If (a), religious belief (c) needs to be backed up by reasons evidence, or (d) it does not.
If (c), this can be done by (e) methods completely unlike those used by scientists and scholars, or (f) like those methods.
Although there are a few exponents of (b), the claims themselves are prima facie (a) claims. "God exists", is for most people an attempt to say something true about the world, and not just an attitude they take to it. For (d), there are a couple of chapters devoted to exploring the merits of Plantinga's argument for reformed epistemology. But the real concern is the answer to the third dilemma, with Richard Swinburne's cumulative inductive case for the existence of God taken as the paradigmatic example of how one ought to approach God in the age of science.
The chapters addressing Plantinga are instructive to the tone of the rest of the book. While Plantinga has weaved an elaborate logical defence, of ad hoc claims, bare assertions, defeater-deflectors and defeater-defeaters, one might be curious as to what purpose Platinga's argument would achieve. At no point do we have any evidence that our brains possess a sensis divinitus, let alone that it's actually at work in religious experiences, that it's faulty for most people, but less faulty for monotheists, and reliable when it comes to Christian beliefs. Yet this idea gets two chapters of logical objections!
But the vast majority of the book is taken up with a critical analysis of Swinburne's ideas. His argumentation style, much like the opening of the book, often involves particular dilemmas, followed by why each horn of the dilemma is problematic. For dilemma 3 above, the danger of choosing (e) is choosing methodology that has no respectability among intellectuals, while the danger of (f) is that it opens God up to empirical disconfirmation.
The exercise begins by seeing whether Swinburne is successful in casting God as a successful theory in the way scientific theories are. Swinburne's approach is correct, but unfortunately God is not up to the task of being a proper scientific theory. There are obstacles to this, such as God being an irreducible analogy, or using personal terms to describe something that doesn't fit our use of personal language.
To examine Swinburne's inductive argument, he sets aside his earlier criticisms before forcefully showing the problems with Swinburne's approach. Some of the errors are quite technical, such as whether some of Swinburne's arguments are successful C-inductive arguments, but there's a lot of food for thought at each stage. The end result (predictably) is that Swinburne's approach simply doesn't have the predictive power attributed to it.
Like Plantinga's argument, there were times when the exercise bordered on the absurd. God being the simplest thing there is because infinites are simpler than non-infinites mathematically. Philipse deals with this argument early, but as a justification this keeps coming up in Swinburne's inductive argument. One could simply point out that since there is no way of measuring God, there is no way of knowing how simple God is, but the joke goes beyond the pale when Swinburne insists that infinite things are simpler than finite things of the same kind. It takes a lot of complexity to have finite persons with finite knowledge, but an infinite person with infinite knowledge is simple?!
Is this book worth reading? It's a tough question to answer. There are many ways of addressing the truth questions of religion, and whether one feels it's worth digging into this book depends on whether natural theology is seen as the best way to assess the truth. This is in contrast to revealed theology (the specific doctrines of theistic religions) and in contrast to the idea that theology is a pseudodiscipline.
Philipse does his best to argue for the relevance of natural theology as the approach one ought to take, and he aimed at the best natural theology has to offer in his arguments. The end result is something quite technical, but still full of interesting approaches to particular problem. The arguments themselves cover a wide range of philosophical topics, covering not only philosophy of religion, but questions of language, epistemology, mathematics, and meaning. In that light, the case for natural theology is not as esoteric as it seems prima facie.
One of the strengths of the book is that it pushes the issue of theology in the scientific age, and is full of dilemmas facing believers at each potential turn. In that respect, the book is incredibly useful for the current debate about whether science and religion are compatible. Anyone who has an interest on this question will find this book invaluable.
However, this is not a book about how religion is practised, nor is it a book about revealed theology, and the arguments sometimes get bogged down in logical problems when empirical arguments would have been more to the point. And for those who see believing in God as an act of faith, there will be nothing in this book to change their minds. But for those who find the question interesting, and for those who seek a modern understanding of how to address the question, this book is well worth reading.