This one really shook me up. It should shake you up as well if you read it (and you really, really should).
The Myth of a Christian Nation by Gregory A. Boyd is simply a must-read for all American Christians. Dr. Boyd brings up some very valid questions about how we conceive of the relationship between America and Christianity and the way he answers his own questions make a lot of sense.
Boyd's basic premise is this: there are two types of kingdoms. The first can be called the "kingdom of the world." Every government on earth, including America, falls into this category. Kingdoms of the world are concerned with "power over," i.e. exercising authority, making laws, controlling people either by the sword or by threat of the sword.
Jesus, on the other hand, came to establish, not a kingdom of the world, but the kingdom of God. The kingdom of God is radically different from any kingdom of the world. The way Jesus described it was as a kingdom of "power under." Those who belong to this kingdom are to be servants of all, to take up their cross, not the sword.
Boyd's basic argument is that you can't mix the two kingdoms together and he fears that that's what mainline evangelical Christians are trying to do. By forcing "kingdom of God" concepts into the "kingdom of the world" (namely the U.S.), Boyd says that Christians are mixing the two improperly and worse, they're corrupting the teachings of Christ with political power.
Boyd's arguments are very persuasive. He says that rather than engaging in political activism, Christians should instead be about loving their neighbor. Instead of trying to force morality on people through laws, we should instead be loving them as Christ loved them.
I'm not doing justice to his arguments. To put it simply, Christians everywhere should read this book. I fear that the American church is guilty of equating God with America and that we have, in a very real way, created an idol out of the American flag. We need to realize that there is a difference between the two and that equating the two can only lead to trouble.