The first mistake common to most analysis of the US is that the president has any significant power. Let’s clear this up once and for all: he doesn’t. The second mistake is that the US government operates without a political religion. Well, it does.
This dynamic is important because little of the world’s events outside of raw geopolitics make any sense without it. You might think the US government is well-understood, but it absolutely is not. And it’s far easier to understand the political future of the country if you understand the ideology behind it.
What you call “political correctness” is what I call (from a political standpoint) progressivism, or (from a religious standpoint) Unitarianism, or (from a comparative-historical standpoint, by analogy to Japan's state Shinto) state transcendentalism. The idea is inarguably the most successful modern branch of the mainline Protestant tradition. Which happens to be pretty much the most powerful religion on Earth today and for the last century, although it has mutated away most of its theism.
You can say four things about this creed: 1) it was the dominant belief system of New England, 2) it is the primary heir of the Puritan tradition, 3) it is the primary ancestor of the creed ("political correctness") now enforced at the same institutions where it was born and 4) since WWII it has been the state religion not just of the US but of the world at large. Listen to what the Beehive says.
The four ideals of progressivism are: Equality (the universal brotherhood of man), Peace (the futility of violence), Social Justice (the fair distribution of goods) and Community (the leadership of benevolent public servants). They believe these ideals are universal, can be derived from science and logic, no reasonable person can dispute them and – if applied correctly – will lead to an ideal society.
I believe they are arbitrary and inherited from Protestant Christianity. They also serve primarily as a justification for the rule of the progressive establishment in the US and everywhere in the “international community” and are a major cause of corruption, tyranny, poverty and war.
So, in this frame, Hillary Clinton was a religious candidate. Her supporters wanted a more progressive government. Similarly, most Trump supporters wanted a more Christian (traditionalist, salvationist, fundamentalist, etc) government. There are policy implications to this struggle, but at bottom it’s just a good, old-fashioned religious war.
The US state religion (that which is taught in public schools and mainstream universities) is not too different from traditional religion. Its egalitarian and humanistic notes are recognisably Christian. In fact, you might simply call it a form of Christianity following the apparent philosophy of Jesus, while discarding most of the weirder magical and institutional overtones. Progressivism is the logical endpoint of the Protestant tradition.
The doctrine of universal salvation, versus the doctrine of salvation by faith, is the best measure of this divide. It corresponds almost perfectly to the red-state/blue-state thing. Universal salvation leads very quickly to humanism, democracy and state-worship. Salvation by faith leads to snake-handling, gay-bashing and Billy Graham-worship. Both are horrible.
There are still traditional Christians around, but their political power is very small. All of the “born-again” institutions are voluntarily organised and have little or no support from the state. Their entire revenue stream depends on maintaining a high level of commitment from their base. This is why they evangelise – they have to, or they’ll perish.
If you want to really, really boil the thesis down, my point is that Protestantism is leftism and leftism is Protestantism. In looking at the evolution of European Christianity without tethering it to paranormal doctrinal controversies, this pattern is clear.
“Liberalism” in today’s American sense of the word is simply a synonym for Unitarianism (or Nonconformism in the British usage). There is clear historical continuity and hardly any doctrinal change. The reason you don’t see Unitarian churches everywhere is that, in the 20th century, the State became the holy institution of this faith, and the universities and press became its transmitters. It’s the wonderful world of caesaropapism.
But there were mutations needed to make this process work. Liberalism had to deny its Christian character and history because, as an official religion, it needed to declare itself universal and non-sectarian. But, because no one can get elected in the US with only the Unitarian vote, candidates say they’re Christian to avoid offending the large number of voters who have not followed this transition. The whole system follows the path of least resistance.
The history of Western government in the 20th century, unless you count the Nazis, is hardly a story of populism. It is a story of ideas being born in Unitarian universities and pounded into the masses by sheer repetition. So the question is: what about egalitarian post-Christianity in the American mainline Protestant tradition made it so successful in capturing and retaining the Western political system? Was it just a military coincidence, or was it due to some particular adaptive advantage?
Those of us who don’t believe in democracy tend to take it for granted that any creed, culture, tradition or faith which captures the modern political apparatus can and will capture the population. Why should the principle of cuius regio, eius religio have somehow been repealed in the 1960s? History shows us over and over again that intolerance works, and there’s no belief more intolerant than progressivism.