As I said in my original post, there are only two teachings that I consider essential to Jesus' ministry: Love God and love your neighbor as yourself.
Now, before I continue, I'd like to make clear that I know the things I'm about to list aren't universals, nor are they exclusive to American Christianity. They're just the things that I see as sticking out particularly badly.
Enforcing Christianity as a state religion-You see this in such things as Ten Commandment monuments at government buildings, attempts to force Christian prayer in schools and government functions, and this quote:
http://www.fstdt.net/QuoteComment.aspx?QID=63730. This is in direct opposition to the First Amendment, the writings of Thomas Jefferson and the Treaty of Tripoli, just to name a few. There's even a political party specifically dedicated to replacing the government with a Christian theocracy; ironically, they call themselves the Constitution Party.
Opposition to homosexual rights - Most states have no laws protecting people from being discriminated against for their sexual orientation, and conservative Christians fight hard to keep it that way. The tide is turning...a recent poll revealed that 59% of gay-marriage opponents think that full legalization is inevitable...but the fact that people still think it's somehow their business what consenting adults do in private, or that certain people deserve to be treated as second-class citizens, says nothing good.
Opposition to women's rights-More and more states are trying to throw up roadblocks to legalized abortion, including in cases of rape and incest. The fact that many anti-choice activists are willing to make exceptions for rape and incest shows that it's not an issue of "pro-life", but an issue of trying to enforce a particular sexual morality, which not everyone is going to agree with.
Opposition to governmental assistance for the needy, the myth of the "self-made man"-The vast majority of such opposition comes from conservatives, who pepper their speeches with appeals to Christianity in the form of wedge issues like abortion and gay marriage. In addition, there's the phenomenon of the "prosperity gospel", which claims that God rewards his faithful with wealth. Look at conservative outrage over Obama's "didn't build that" quote, which was taken out of context. In context, he was pointing out that any private business relies on publicly-funded infrastructure like roads and plumbing.
Opposition to science-This comes in many forms, ranging from attempting to teach creationism in public schools to opposition to genetic research that could potentially lead to cures for many diseases and disorders. The vitriol against science that you see in many quotes on this site is only a small example; with the understanding that anecdotes are not evidence, I've run into dozens of people in real life who flatly oppose scientific research, particularly genetic research, often making the claim that science produces nothing good, while ignoring the incredible benefits science has brought to everyone's life.
This is just a short list of the things I see as the worst aspects of American Christianity. Like I said, none of these are exclusive to America, and they don't apply to all Christians in America, but they're the points that the vocal minority who the media treat as "real" Christians tend to emphasize the most.
On an unrelated note, it's bad form to make multiple posts in a row. If you want to reply to multiple people at once, reply to them all in a single post; cut-and-paste their quotes if you want. Posting multiple posts in a row just takes up space on the board.