On the surface, dark horse Democratic presidential candidate Marianne Williamson and President Trump could not be more different. The president tweets insults, stokes crowds into a rage and rattles the sword. He uses the often-jingoistic language of muscular Christianity (“In America we worship God, not government”) to evoke the vision of a middle America made “great again.” Meanwhile, Williamson, a self-help spiritualist (and sometime adviser to Oprah Winfrey), preaches a gospel of “love” and “oneness,” blending a chipper New Age sensibility with progressive politics. In the Democratic debate Tuesday, she condemned the “dark psychic force” of hatred that she said Trump has unleashed, saying it could be combated only by “something emotional and psychological” — which only she could bring forth — accompanied by a dose of “deep truth-telling” on the subject of race. She’s called for a “moral and spiritual awakening” in the United States.

But Williamson has more in common with President Trump than she — and indeed many voters — might admit, and it’s not just that both have used personal celebrity as a springboard into politics. At their core, both are also prime representatives of one of the most important and formative spiritual trends in American life: the notion that we can transform our material circumstances through faith in our personal willpower. Trump’s authoritarian cult of personality and Williamson’s woo-inflected belief in the power of “self-actualization” both come from the quintessentially American conviction that the quickest and surest route to Ultimate Reality can be found within ourselves.

Williamson’s connection with this tradition is more obvious. She came to prominence popularizing and commenting on a four-volume 1975 metaphysical tome called “A Course in Miracles,” by Helen Schucman, a research psychologist in Manhattan who believed herself to be transcribing the words of Jesus. “A Course in Miracles” tells readers that reality is an illusion and that by changing their perception of it, they can alter their circumstances and achieve astonishing things, personally and professionally. Several of Williamson’s books elaborate on those themes. In “The Law of Divine Compensation” in 2012, for example, Williamson conveyed to readers a supposedly surefire universal principle: “To whatever extent your mind is aligned with love, you will receive divine compensation for any lack in your material existence. From spiritual substance will come material manifestation. This is not just a theory; it is a fact.”

Trump, whose egotism often appears self-taught, or at least instinctual, was also influenced by a variant of this pseudo-theology, albeit one more palatable to East Coast business executives. He has spoken openly about his family’s long and close relationship with Norman Vincent Peale, a 20th-century writer well-known for his best-selling 1952 book, “The Power of Positive Thinking.” While Peale was formally a Christian — he was the pastor of Marble Collegiate Church in New York for more than 50 years — his writings were suffused with the idea that you can transmute and augment yourself through sheer mental exertion. “Formulate and stamp indelibly on your mind a mental picture of yourself as succeeding,” he wrote. “Never permit it to fade.” By thinking it, his readers would make it true.

President Trump has attributed his business success to the power of positive thinking. (Jabin Botsford/The Washington Post)

Trump and his parents attended Marble Collegiate Church, and both of his parents had their funerals there. Peale also officiated at Trump’s 1977 wedding to Ivana, his first wife, as well as that of one of Trump’s sisters. Trump has publicly referred to Peale as “the greatest guy” and someone you could listen to “all day long” — and he has attributed some of his business success to his adoption of Peale’s philosophy. In 2009, Trump told Psychology Today that he credited his father’s formative friendship with Peale with his own belated success in business. “Defeat is not in my vocabulary,” he said. “ … I refused to be sucked into negative thinking on any level, even when the indications weren’t great.” He’s a man who has never once publicly allowed failure to cross his consciousness.

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Spiritual and faith traditions that emphasize personal introspection and emotional authenticity over doctrine, creed, “experts” or institutions are hardly new. Waves of what you might call “intuitional religion” have been washing across the American religious landscape since the First Great Awakening of the 18th century. In that movement, which lasted from the 1730s into the 1740s, fire-and-brimstone tent revivalists exhorted fair-weather Christians to receive a “new birth” in Christ. America’s separation of church and state made it easy for this self-focused pietism to flourish outside the aegis of established religious institutions.

But few iterations of this American intuitional religion have had such a long-lasting effect on today’s religious landscape as a little-remembered phenomenon called New Thought, a once-ubiquitous craze that, through its 20th-century heirs, came to deeply influence the thinking of Trump, Williamson and tens of millions of others.

New Thought, which flourished in the mid-1800s, was heavily shaped by the Transcendentalist philosophers of the previous generation, writers like Henry David Thoreau and Ralph Waldo Emerson, who believed that the human self was the closest thing we have to a reflection of the divine. For these thinkers, organized religion — indeed, every mainstream institution — inhibited people from trusting their divinely sanctioned intuition, which they saw as the most direct path to truth. “All that you call the world is the shadow of that substance which you are, the perpetual creation of the powers of thought,” Emerson wrote in 1842, in his essay “The Transcendentalist.”

New Thought took this Transcendentalist trust in the self and commercialized it. Its originator, a New Hampshire-born clockmaker, mesmerist and faith healer named Phineas Quimby (1802-1866), preached a gospel of total psychic self-reliance, one largely shorn of Christian theology and trappings. There was nothing human beings couldn’t do, he asserted, so long as they believed fully in themselves. Physical illness, personal misfortune — these were results of an improperly aligned mental system. Both the success of Quimby’s traveling practice and the later writings of his numerous followers and imitators, including Prentice Mulford and Charles Fillmore, brought New Thought — also popularly known as the “mind cure” and the “Boston Craze” — to the masses.

Throughout the late 19th and early 20th centuries, hundreds of thousands of Americans scooped up dozens of titles promoting the New Thought ethos: If you feel it, it will come true. There was Charles Benjamin Newcomb’s 1897 “All’s Right With the World,” which instructed readers not to wish for betterment but to summon it through force of will. (“I am well.” “I am opulent.” “I have everything.” I do right.” “I know.”) There was William Walter Atkinson’s 1901 “Thought-Force in Business and Everyday Life.” (“Anything is yours, if you only want it hard enough. Just think of it. ANYTHING. Try it. Try it in earnest and you will succeed. It is the operation of a mighty Law.”) Capitalists like Napoleon Hill advised readers to “Think and Grow Rich” (1937). And Christians, including Quimby’s onetime patient Mary Baker Eddy, sought to blend that faith with New Thought practice, as Eddy did in establishing Christian Science.

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The “mind cure” was sufficiently popular that psychologist William James meditated on its ubiquity in American households. “One hears of the ‘Gospel of Relaxation,’ of the ‘Don’t Worry Movement,’” he writes in one of the lectures in his 1902 collection, “The Varieties of Religious Experience,” “of people who repeat to themselves, ‘Youth, health, vigor!’ when dressing in the morning, as their motto for the day.”

Peale was also a product of the New Thought tradition. Positive thinking, he argued, didn’t need to be constrained by reality. Rather, Peale told his readers to “make a true estimate of your own ability, then raise it 10 percent.”

The idea that one should adopt a magnified view of one’s talents and accomplishments, and that reality will reconfigure itself to match that heightened image, may help explain some of the otherwise confounding falsehoods that Trump retells continually. He rarely settles for a paltry 10 percent inflation of his ability — whether he’s sending Sean Spicer out to insist that he attracted “the largest crowd to witness an inauguration,” or asserting that construction of his border wall continues apace, or claiming that he has the “all-time record” for approval by a Republican president. It’s understandable that Trump leans into New Thought philosophy, given that such braggadocio propelled him into the White House and costs him little support among his followers.

The New Age sensibility of Democratic candidate Marianne Williamson has deep roots in an American tradition called New Thought. (Lucas Jackson/Reuters)

To those encountering Williamson for the first time in this campaign, she comes across as a conventional New Age type — an eccentric aunt purveying essential oils. That side of her is real, as when she tweeted that “love IS the answer, and that is as relevant to public policy as to personal behavior.” But there’s a much more specific tradition she emerges from, which is typified by this darker comment in “The Law of Divine Compensation”: “Many people fail to manifest money because on some deep level they don’t think they should.” She has also argued that depression should be considered “a spiritual disease,” rather than “medicalized” and treated with anti-depressants. (When challenged, she said anti-depressants were justified in some cases.) And she’s suggested that people who are overweight may suffer from a deficit of “spiritual intelligence.”

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You can see the legacy of intuitional religion all over the country. It’s in New Age and occult books, to be sure, but it’s also in pop-culture sensations like the 2006 self-help book “The Secret,” beloved by Winfrey. It’s in the mind-set of the growing ranks of the “spiritual but not religious” — now about 20 percent of Americans — and in that of the even bigger numbers of the religiously unaffiliated, who are significantly more likely than their traditionally religious peers to agree with statements like “Whatever is right for your life or works best for you is the only truth you can know.” It’s in the relentless positivity of wellness culture, echoed in the Instagram mantras of SoulCycle and on Gwyneth Paltrow’s Goop website (where osteopath Habib Sadeghi informs readers, “I can tell you that UNRESOLVED EMOTIONAL PAIN and UNEXPRESSED DESIRES are at the core of what I call ‘DIS-EASE’ or a body-mind that’s not at ease").

You can see it in the “prosperity gospel” — the idea that prayer and tithing can make you rich in the long run — which is taught in as many as a third of evangelical Protestant churches, according to a 2018 survey by LifeWay Research. (Prosperity gospel preachers like Kenneth Copeland and Paula White, who has asked her parishioners to send a sizable portion of their January salary to her church, have visited the White House.) And the idea that people’s attitudes, rather than economic or social structures, are largely responsible for their material or medical circumstances is now taken by many conservatives as gospel.

On the surface, Americans are more religiously divided than ever. White evangelicals overwhelmingly support Trump; meanwhile, the ranks of the religiously unaffiliated, who tend to lean left, continue to grow. But many Americans of almost every political and spiritual affiliation share the inheritance of New Thought ideology: a distrust of institutions and experts, a reliance on personal intuition and feeling, and a conviction that “self-actualization” will lead inexorably to a bigger house, a better job, a banging body.

While it’s highly unlikely that Williamson will win the Democratic presidential nomination, her presence on the campaign trail, and Trump’s presence in the White House, serve as reminders that the ethos of Quimby and Peale thrives on both sides of the political aisle.

It may not be the “oneness” Williamson has in mind. But it’s the closest thing we have to a civil religion.