A side note: if you go to Amazon.com's page on the book, it shows a somewhat different readership than your typical piece of anti-atheist polemic. If you look at anti-atheist works by Ravi Zacharias or Norman Geisler, you can go to the "customers who bought this..." section and see a lot of other run of the mill evangelical apologetics. This section for McGrath's book indicates a somewhat more mainstream readership.
Now, what are McGrath's arguments against atheism? Much of it is guilt by association: in the very first sentence McGrath gives, as his landmark dates in the history of atheism, the French Revolution and the collapse of the Soviet Union. There's a general sense of "the French Revolution/Marxism/de Sade/Richard Dawkins" is bad, so atheism is bad. Often, there is little more than a vague mention of these things, but sometimes he goes for something like an argument. For example, on page 233-234 he claims, "as the rise of Nazism and Stalinism in the 1930's made clear, breaking with tradition just meant breaking with civilization and all its inbuilt safeguards against totalitarianism." Reflecting on this line, it's difficult for me to believe that an educated person could be so mindlessly reactionary. Certainly McGrath must realize that some traditions are harmful, some traditional beliefs false.
A little later there is a section on "the embarrassing intolerance of atheism," where McGrath tries to argue that atheism necessarily leads to forcible extermination of religion, because it "has a disturbing tendency to see itself as the only true faith." Why McGrath thinks atheism is different than any other claim about the world is not explained. He does say, though, that since atheists want to get rid of religion, they're inevitably going to do things like what Stalin did.
This odd sentiment makes considerably greater sense when viewed in light of McGrath's insistence that questions of religion cannot be rationally decided. He admits that there are no good arguments for the existence of God, but says atheism isn't based on reason either. He asserts this with great confidence, but doesn't seem to think he needs to adress any arguments against the existence of God. He does finally get around to spending three pages on the problem of evil late in the book, but his amounts to "humans do bad things--especially when they don't believe in God!" This blatantly dodges the question. No doubt any human being who was perfectly capable of preventing the worst crimes that happen today and made no attempt to do so would be thought almost as monsterous as the actual perpetrators.
If McGrath were insistent on assuming there are no good arguments against the existence of God, it would have been nice to at least see him deal with critiques of belief in absence of evidence, such as Russell's remarks about teapots and Greek gods and Flew's on the invisible gardener. These are ignored. He does mention Clifford's "Ethics of Belief," but again he dodges the question by saying that Cliffod demanded too high a standard of evidence, ignoring the question of whether we should want any evidence at all before believing in things.
Rather than deal with these basic issues, McGrath prefers to spend his time attacking Marx, Freud, and Richard Dawkins. The first two are rather odd choices, since they are regarded as quacks by many modern rationalists, but he treats his defeat of them as a defeat of the intellectual foundations of atheism. Basically, he says their sociological/psychological explanations for belief in God are based on just assuming that God does not exist. It does not occur to him that if a widely held belief is without rational foundation (as McGrath admits religion is), perhaps social scientists are justified in looking for other causes, even if they can't quite disprove the belief. Give that he's dealing with sociology, one might also expect a treatment of the argument that the wide array of conflicting religious beliefs suggests they are just a human invention, but he does not.
His treatment of the supposed conflict between science and religion is a bit better, insofar as Darwin did nothing to refute the ontological argument. However, he trys to make it look like special creation, which Darwin did cause problems for, was a special doctrine of William Paley, rather than the most straightforward reading of Genesis. He gets even further off course when he attacks Richard Dawkins for noting that scientists, unlike theologians, produce evidence for their claims. As with Clifford, he attacks the straw man of logically demonstrative proof and fails to reflect on the importance of having at least some evidence for claims about the world.
Things get truly bizzare when he begins talking about postmodernism, which, if does not endorse, he thinks preferable to modernism. McGrath conceives postmodernism as follows:
Postmodernity is a complex, perhaps undefinable notion (in that "defnintion" implies limitation, something to which most postmodernist writers take exception). Nevertheless, a number of common themes can be identified within the movement. Perhaps the most important of these is the rejection of modernism's quest for objective, esentially knowable truth and beauty...One wonders: if McGrath isn't so hot on the idea of objective truth, why didn't bother trying to make religion compatible with evolution? Why didn't he just say, "Nothing is objectively true, therefore the discoveries of modern biology are not objectively true"? Taking things one step further, does he believe any of the statements in his book are objectively true?
The rubbish that McGrath spouts goes much beyond what I have quoted here. It is difficult to give a good impression of it in such limmited space. It might help, though, to say it left me thinking rather highly of Ravi Zacharias, who, inspite of everything that he gets wrong, does a fairly good job of dispatching the postmodern nonsense that is fashionable in some circles.
McGrath's thoughts on the rationality of theism and atheism are not presented as systematically in his book as my discussion does (or attempts to). However, I think dealing with them first allows for making sense of McGrath's conviction that atheism necessarily leads to violence against theists. It is as if an astrologer lazily declared that the validity of astrology cannot be decided on the evidence, and maybe isn't even a matter of objective truth, and from there jumped to the conclusion that critics of astrology must be plotting to put astrologers in concentration camps, because hey, they've got no arguments against astrology, right?
Were this book all I had read of McGrath's writings, I would have placed his work as the sort of liberal irrationalism that is impotent to fight fundamentalism. A Google search, however, revealed that McGrath is no liberal; he believes in the doctrine of inerrancy.
This certainly raises some troubling questions. In some ways, McGrath deserves a commendation for honesty; he is far more open about his rejection of rational thought than William Lane Craig, Gary Habermas, and a number of creationists. But why, though, does he not mention his belief in inerrancy when going off about the "embarrassing intolerance of atheism"? Is McGrath embarrassed by Deuteronomy 13, which teaches that practitioners of other religions must be put to death? Is he embarrassed by John 3, which teaches the damnation of unbelievers? These passages lead to execution of dissenter much more readily than mere rejection of belief in God (or mere belief in God, for that matter). Perhaps McGrath is less concerned with fighting intolerance than discrediting Christianity's competition.
In close I should say something about McGrath's historical analysis: that atheism is a social phenomenon spurred by the reformation and will die when modernism dies. On the distant end of the historical spectrum McGrath is probably right to link atheism to the reformation, though not in the ways he does. Martin Luther was not terribly keen on rational thought, but when he encouraged people to interpret scripture for themselves, he was encouraging them to think for themselves in other ways. McGrath is probably also making a mistake to ignore the rediscovery of antiquity. This forced the educated to come to terms with non-Christian religions. This made possible Hobbes' argument that religion is merely socially acceptable superstition. It made possible Russell's protest that he could not disprove Zeus and Hera. It made possible the argument from religious confusion. It made possible The Outsider Test. It significance is easily and often underestimated.
On the other end, if McGrath is right to tie the demise of atheism to postmodernism, atheism will be here for a long time to stay. Postmodernism has taken some heavy hits in recent years, such as Alan Sokal's Towards a Transformative Hermeneutics of Quantum Gravity. The comming years will likely be dominated by a contest to fill the vacuum of postmodernism's demise. Conservative religiosity has already gotten a good start in that area, though unbelief has a major opportunity. It will be an interesting show.