On the one hand, this post trying to explain why Americans are more religious than Europeans made me think of a line I heard somewhere (maybe someone in the comments can give me a source): “Europeans don’t believe in God, so they do whatever they want. Americans do whatever they want and call that Christianity.” Ross Douthat’s new book is all about this of course.
On the other hand, I volunteer at a crisis pregnancy center which serves, for the most part, poor black women. I do see a lot of influence from the “prosperity gospel” and other self-comforting American heresies. “God doesn’t give you anything you can’t handle” is often deployed as evidence that God must want the woman to have an abortion, since she can’t handle a baby.
But at the same time, the fact that we share a Christian language allows me to relate a lot more than I expected to, to women from a very different class and cultural background. And it turns out to be relatively easy to move into discussing the need to take up one’s cross or accept suffering as Christ did. The vocabulary is there for when you need it, if only someone will help you hear it. (On a side note, I’ve been surprised by how responsive even lapsed cradle Catholics are to the language of the liturgical calendar, like pointing out that we’re in Advent at that moment, or comparing unwanted pregnancy to Lent. This doesn’t resonate with everyone but the liturgical seasons still seem to have a pretty strong hold on many Catholic women’s imaginations.)
Even American heretics accept Jesus as a model for their lives. That means they have the imaginative resources to act in deeply sacrificial ways, if the people in their lives help and challenge them.
JonF 
Nathan 
Charlieford 
David J. White 
There was an ABC special back around naybe 2000 on trends in American religion, and one of the things they did was contrast practices at shrinking and growing churches (both theologically conservative).
The hip and growing church had a lot of what you would expect, but the most interesting thing (for me) was the pastor’s explanation of why they were cancelling evening service on Super Bowl sunday and having a Super Bowl party instead: He said “If Jesus were alive today I believe he’d be at the Super Bowl, sitting right on the 50-yard line.”
Because American religion is so vulnerable to democratic pressures (due to disestablishment), churches are forced to construct a God or a Jesus in the image of Americans. There is, indeed, something very idolatrous about it.
But as you mention, that idolatry is not the final word. I think most American Christians are uneasy about it, sense there’s something wrong, and often respond positively to more faithful representations of the gospel–when they hear them.
The main problem is the churches. Especially the whole “church growth” industry.