The Atlantic tries to explain in a long, interesting essay. Here's an excerpt.
Each of us is on a spectrum somewhere between the poles of rational and irrational. We all have hunches we can’t prove and superstitions that make no sense. Some of my best friends are very religious, and others believe in dubious conspiracy theories. What’s problematic is going overboard—letting the subjective entirely override the objective; thinking and acting as if opinions and feelings are just as true as facts. The American experiment, the original embodiment of the great Enlightenment idea of intellectual freedom, whereby every individual is welcome to believe anything she wishes, has metastasized out of control. From the start, our ultra-individualism was attached to epic dreams, sometimes epic fantasies—every American one of God’s chosen people building a custom-made utopia, all of us free to reinvent ourselves by imagination and will. In America nowadays, those more exciting parts of the Enlightenment idea have swamped the sober, rational, empirical parts. Little by little for centuries, then more and more and faster and faster during the past half century, we Americans have given ourselves over to all kinds of magical thinking, anything-goes relativism, and belief in fanciful explanation—small and large fantasies that console or thrill or terrify us. And most of us haven’t realized how far-reaching our strange new normal has become.
Much more than the other billion or so people in the developed world, we Americans believe—really believe—in the supernatural and the miraculous, in Satan on Earth, in reports of recent trips to and from heaven, and in a story of life’s instantaneous creation several thousand years ago.
We believe that the government and its co-conspirators are hiding all sorts of monstrous and shocking truths from us, concerning assassinations, extraterrestrials, the genesis of aids, the 9/11 attacks, the dangers of vaccines, and so much more.
And this was all true before we became familiar with the terms post-factual and post-truth, before we elected a president with an astoundingly open mind about conspiracy theories, what’s true and what’s false, the nature of reality.
We have passed through the looking glass and down the rabbit hole. America has mutated into Fantasyland.
How widespread is this promiscuous devotion to the untrue? How many Americans now inhabit alternate realities? Any given survey of beliefs is only a sketch of what people in general really think. But reams of survey research from the past 20 years reveal a rough, useful census of American credulity and delusion. By my reckoning, the solidly reality-based are a minority, maybe a third of us but almost certainly fewer than half. Only a third of us, for instance, don’t believe that the tale of creation in Genesis is the word of God. Only a third strongly disbelieve in telepathy and ghosts. Two-thirds of Americans believe that “angels and demons are active in the world.” More than half say they’re absolutely certain heaven exists, and just as many are sure of the existence of a personal God—not a vague force or universal spirit or higher power, but some guy. A third of us believe not only that global warming is no big deal but that it’s a hoax perpetrated by scientists, the government, and journalists. A third believe that our earliest ancestors were humans just like us; that the government has, in league with the pharmaceutical industry, hidden evidence of natural cancer cures; that extraterrestrials have visited or are visiting Earth. Almost a quarter believe that vaccines cause autism, and that Donald Trump won the popular vote in 2016. A quarter believe that our previous president maybe or definitely was (or is?) the anti-Christ. According to a survey by Public Policy Polling, 15 percent believe that the “media or the government adds secret mind-controlling technology to television broadcast signals,” and another 15 percent think that’s possible. A quarter of Americans believe in witches. Remarkably, the same fraction, or maybe less, believes that the Bible consists mainly of legends and fables—the same proportion that believes U.S. officials were complicit in the 9/11 attacks.
There's much more at the link.
The most interesting - and worrying - thing about the article is the blind faith and non-evidence-based certainty with which each of these 'belief groups', to coin a phrase, believes in their particular credo. You can't argue with many of them, because no matter what evidence you advance, or what rational reasoning you deploy, they will stick their fingers in their ears, scream "LA-LA-LA-LA-I can't hear you!", and go on regardless.
Yes, this includes religion. I have religious faith, as is obvious to anyone who's read these pages for a long time . . . but I'll be the first to admit that my faith may be based on falsehoods. I have chosen to accept the Bible as the word of God, and Jesus Christ as a real, historical manifestation of God made man. I base my life upon those principles and his teaching. Nevertheless, if I refused to admit that I might be wrong, I'd be as ideologically dogmatic as a militant atheist who refuses to admit even the possibility of the existence of God in any form. There are many things we can accept and believe, but not be able to scientifically prove. We need to acknowledge that reality. If we don't, we make ourselves as guilty of the problem as anyone else. Doing so does not mean we don't continue to live according to our beliefs. We simply accept that we're fallible, too.
I'm not threatened by someone who doesn't believe as I do. I shall continue to be as open and friendly towards him as his conduct allows me to be, and not worry about things that divide us unless and/or until they become a real obstacle. I trust that one day, my hope and faith in God will be rewarded in the hereafter. If there isn't one, I guess I'll never know . . . but that won't stop me believing, and hoping, and trusting. That being the case, why should I deny the right to their own beliefs to anyone else?
The Atlantic's essay is well worth reading in full, and pondering. Where do we fall on the spectrum of belief-versus-fact? I think we'll all do well to consider that very carefully, and very honestly. Blinkered vision and blinkered minds are a recipe for disaster, personally and nationally.