Without much in the way of hard evidence, Christians regard the Jewish sect leader Jesus of Nazareth as the Son of God.
However, history is littered with messiah claimants who, mainly on the basis of strenuous self-promotion, managed to convince some fellow citizens that they were God or his representative on Earth.
The likes of Sun Myung Moon who claimed that, when he was 16, Jesus appeared to him on a Korean hillside. Moon founded the Unification Church whose members - known as "Moonies" - numbered in the millions and, for all I know, still do.
Don DeLillo's novel Mao 11 begins with a Moonie mass wedding at Yankee Stadium. Looking on, the father of one of the thousands of brides muses that the Moonies are "a nation founded on the principle of easy belief. A unit fuelled by credulousness. They speak a half-language, a set of ready-made terms and empty repetitions".
"When the old God leaves the world," he wonders, "what happens to all the unexpended faith?"
The answer is that it goes into politics. The 20th century totalitarian ideologies of left and right were quasi-religious movements that replaced an absentee God with flesh and blood messiahs.
This year is the 50th anniversary of China's Cultural Revolution, when Chairman Mao unleashed hell on his country to keep everyone on their toes, ideologically speaking. Like all messianic cults, Mao worship combined mindless adoration of the great leader with demonisation of unbelievers and backsliders whose failure to get with the programme came in many forms.
In the Guardian this week, a former Red Guard recalled that "we thought that, if you were wearing skinny trousers, you were a monster".
As the term implies, true believers don't need - or, for that matter, want - to be persuaded. They want to be told. They yearn for opportunities to display blind faith. Donald Trump understands this, hence his standard rhetorical device:
"I'll build a wall and make Mexico pay for it. Believe me."
"I'll crush ISIS. Believe me."
"I'll bring China to heel. Believe me."
"I'll deport 11 million illegal immigrants. Believe me."
There's scant reason to believe Trump since he offers no detail on how he's going to accomplish these things and has no political track record or, indeed, any apparent understanding of how government works under a system in which elected leaders have more limitations on their freedom of action than the owners of private companies.
But believe him they do. They've drunk the Kool-Aid, a concept that harks back to cult leader Jim Jones calling on 900 followers to commit mass suicide by drinking cyanide-laced Kool-Aid. They duly obliged.
Cultism isn't confined to Trump supporters. Bernie Sanders, the leftist challenging Hillary Clinton for the Democratic nomination, has garnered a following as devoted as Trump's via much the same methodology: characterising the system and political process as flawed, if not corrupt; dismissing mainstream politicians as sell-outs; identifying America's problems in simplistic terms and promising to fix them in short order through sheer force of will and personality and purity of intention.
Hillary Clinton's long, convoluted and not always admirable political odyssey has brought her to the point where she's the last remaining obstacle for these two outsiders whose proposition to America owes more to a personality cult than consensus-building around a coherent set of policies.
