The title of this book is a little misleading, because it's less about faith in general and more about Christianity, Protestantism specifically, with a side order of Islamic fundamentalism. That said, one can understand why, given the simultaneous rise of Christian and Islamic fundamentalists in America and the Middle East. It's an incredibly topical issue at the moment.
The authors argue that it's not just the issue of faith that is on the rise, but a very specific kind of faith - American-style conservative, personal, customer-focused, market-led faith. They argue that one of the reasons religion has flourished so much in America, as opposed to the almost aggressive secularism of Europe, is the separation of church and state that is so rooted in the American constitution.
Because religion had no institutionalised protection as it did throughout Europe, there was great competition between the different creeds and sects and religion. They had to fight for each believer, each customer - and it led to the kind of mega-churches we see today, with bowling alleys and crèches and shopping malls. Religion is big-business in America. The churches give the people what they want, and business is booming. Compare that to England, for example, where the Church of England has no need to fight for its dominant position, and is therefore a pretty faint, woolly kind of church. There's no aggressive marketing, no jockeying for position, no rivalry with other denominations, no personalised service, no tempting add-ons. It's fading away.
Religion is also very tied up with modernity. It is used to be that developing nations determined to embrace modernity saw shedding religion as part of that. The Nazis and Soviet Union were both very much anti-religion. Atatürk attempted to turn Turkey into an aggressively secular state. But now the pendulum has swung the other way, and many nations, using America as the example, are seeing that modernity and religion can go hand-in-hand, as long as the religion is along the American example.
From my perspective as a somewhat confused agnostic/atheist, it's all a little worrying. The conflicts between Hindu and Muslim in India and Pakistan, between Arab and Jew in Palestine, between American and Al Qaeda - religion is at the root of all a lot of the hot points around the world, and when religion is involved rationality tends to fly out of the window a lot of the time.
"God is dead", Nietzsche once claimed - but on this evidence he's very much alive and kicking. Whether that's a good or bad thing is up to you, but it's certainly food for thought.