There is no doubt that Christianity is alive and well in the United States--perhaps more than any other nation in the world. At least, it is a part of the usual, public discourse. We see it on TV, we hear and see pundits on TV talk about how the US is a Christian nation, we can buy holy water by way of a 1-800 number, we can watch the pink haired lady go through an entire box of tissues....I could go on.
Ok, but on a more serious level (that is, absent of pink-haired TBN jokes) Christianity is a big part of the US. If nothing else, look at all the immense amount of stuff you can buy that is related to the Christian faith--Protestant or Catholic. That statement should tell you of the American version of religion. But I'm not sure this is such a good thing. In a way, consumerism is the American religion.
I think the author of "Material Christianity" finds the American affection towards materials and materialism, as well as the ones that profit from the sale of goods that represent a non-materialistic religion, as especially problematic. And I have to agree. Some of the earlier incarnations of representations of Jesus or God are a bit more forgivable, but the modern-day ones simply are not. There are just some people out there that you must wonder if they are more intent on selling copies of their own book or getting people to pick up there bibles.
I mean, for example, a friend of mine recently got married and the church the ceremony was held in had a form in the pew that signed you up for direct deposit for your tithe. Ok, maybe not so crazy to some, maybe you are an avid and regular 10% giver as the Bible instructs, fine. This is not a particularly good example, I realize, but it may help put it in perspective.
More politically speaking, it is those that claim to be Christians and are viewed as such that promote the very system that keeps money in the pockets of the richest people in the country and encourages an affinity for commodities and material things--that is, "things of this world."
Either way, it is difficult to pin-point the cause of Christian values being coupled with American Capitalist values, but it certainly is alive and well.