Science and Religion
One source of political and socio-economic disagreements among Americans (maybe citizens of those other countries too) is the idea that science and religion are diametrically opposed . The best example is probably the constant debate over creationism/intelligent design/evolution, since (for many people) that particular discussion treads close to fundamental questions about why we're all here, where we came from, the meaning of life, morality, etc. In today's world, where individuals are freely and unapologetically classified into black-and-white categories (for instance, "liberal" and "conservative"), it seems as if one has to choose between God and science. There are plenty of people on both "sides" who use their own set of authoritative writings to declare that the other "side" is sadly deluded. Such cut-and-dried stances miss the point. Science and religion occupy sufficiently separate realms that attempting to use one to discredit the other is a fallacy.
For most of human history (say, before the Renaissance, Reformation, and Enlightenment) there were hardly any high-profile conflicts between science and religion, mostly because, whether explicitly stated or not, pretty much everyone agreed that the supernatural played a role in what we today would call natural phenomena. It was God of the gaps to the max--and it was perfectly acceptable at the time. Explicit atheism would have been hard to justify in a universe in which lightning was unexplainable except through divine intervention, magic, or some other supernatural interaction.
The Enlightenment gave widespread appeal to the idea that observed phenomena could be explained naturally. Suddenly, it seemed that God could be tossed out of natural processes--or, at the very least, demoted to lower-level, subtler control of nature. He didn't actually conjure lightning bolts out of a void and throw them around around, but he instead governed the fundamental laws of how the lightning came about.