In 1890, the Supreme Court upheld a federal law that abolished the Church of Jesus Christ of Latter-day Saints’ corporate charter and authorized the U.S. government to seize its property. This collective punishment was constitutional, the court ruled, because the Mormons’ crime, polygamy, was “barbarism” and “contrary to the spirit of Christianity.”

Facing institutional destruction, the Mormons renounced polygamy; this, in turn, enabled Utah’s admission as a state in 1896. Over time, the twin cases that produced the court’s ruling — Late Corporation of the Church of Jesus Christ of Latter-Day Saints v. U.S. and Romney v. U.S. — faded into obscurity.

They’re relevant again. If he wins the presidency, Mitt Romney, the former Massachusetts governor and Mormon bishop, would not be the first president to confess a historically disfavored faith. But Romney would be the first who belongs to a church that the U.S. government actually tried to crush.

The Latter-day Saints broke all the rules of Protestant-dominated 19th-century America. They considered the church’s founder, Joseph Smith, a prophet, and his Book of Mormon a work as sacred as the Bible. Mormon men professed a religious duty to take multiple wives.

The “Mormon question” was also deeply political. Polygamy in the Utah territory created a constitutional crisis eerily similar to those raised by attempts to bring slavery into Kansas.

Just as anti-slavery Americans saw that institution as the basis of a corrupt, expansionist “slave power,” so did anti-polygamists see plural marriage as enslavement of women and the foundation of a theocracy that could spread from Utah.

In 1856, the Republican Party platform urged Congress “to prohibit in the territories those twin relics of barbarism — Polygamy, and Slavery.” In 1857, President James Buchanan, a Democrat, sent troops to skirmish with Mormon militia in Utah. In 1862, President Abraham Lincoln signed the Morrill Anti-Bigamy Act, the first of several such laws.

Slaveholders invoked property rights; Mormon polygamists claimed religious freedom. They took their case to the Supreme Court, which ruled against them in 1879 — holding that the Constitution did not protect polygamy any more than it protected human sacrifice.

Next came mass arrests of Mormons, denial of their rights to vote and sit on juries, threatened confiscation, and, in the end, Mormon abandonment of plural marriage — which only a minority actually practiced.

This long-ago struggle, in which Mormons and non-Mormons shed blood, is complicated even in hindsight. Anti-Mormonism was not a pure case of intolerance; polygamy did threaten women’s equality. Yet the Supreme Court’s assertion of a “Christian” basis to constitutional law and federal punishment of all Mormons for the actions of a minority are hard to justify by modern standards.

Contrary to foes’ predictions that the LDS would wither without polygamy, Mormonism flourished in the 20th century, growing to 3.1 million adult adherents as of 2008. Yet many Americans still do not know quite what to make of them.

Twenty-two percent of voters told Gallup last year that they would not back a Mormon of their own party for president, in contrast to 5 percent willing to admit that about an African American.

Ironically, given their faith’s origins as a kind of counterculture, Mormons’ current material success and “traditional” views on abortion and gay marriage probably cost them popularity — on the progressive left. A recent documentary film, “8: The Mormon Proposition,” depicted the church as a shadowy theocratic power behind the defeat in 2008 of same-sex marriage in California. On the right, though, evangelical Protestants, also echoing 19th-century rhetoric, depict the Saints as un-Christian or, as Baptist leader Robert Jeffress put it last year, a “cult.”

Meanwhile, pop culture serves up stereotypes with varying degrees of humor and taste. Last year’s Broadway hit, “The Book of Mormon,” was a relatively gentle send-up. But would anyone make a satire called “The Koran”?

In November, we may find out how many votes, if any, hinge on generalizations, pro and con, about Mormonism. Liberals wouldn’t back a conservative Republican whatever his faith; 91 percent of white evangelical Protestants told a 2011 Pew Research survey that they would vote for Romney over Obama, if those were the options.

Americans are products but not prisoners of our history. Like Mormonism, U.S. democracy was invented in the New World, and it’s still being reinvented. Hence the prospect of a presidential contest between an incumbent whose race would have made him an outcast 125 years ago — and a challenger whose creed would have done the same.