Americans like to say faith is a private matter. The voting booth tells a different story.

For as long as we’ve picked presidents, a candidate’s church, or lack of one, has landed on the ballot whether anybody admitted it or not.

Sometimes it sank them. Sometimes they squeaked by.

Here are the campaigns where what a candidate believed almost cost them the whole thing. How many do you remember learning about, Floridians?

Al Smith’s Burning Crosses

Al Smith ran for president in 1928 as the first Catholic on a major party ticket.

The reaction was ugly.

As his campaign train rolled through the country, the Ku Klux Klan lit crosses along the tracks. Whisper campaigns claimed the Pope would run America from a back room in the White House.

One rumor insisted the newly opened Holland Tunnel secretly ran all the way to the Vatican.

People spread it with a straight face.

Smith, the governor of New York, lost to Herbert Hoover in a landslide.

The economy and Prohibition played their parts. So did the fear of a Catholic in the Oval Office.

Smith never returned to a presidential ballot. A year later the market crashed, and the man who beat him owned the wreckage.

Three Words Sank Blaine

James G. Blaine had New York, and New York had the 1884 election.

Then a supporter opened his mouth.

At a campaign reception, a Protestant minister named Samuel Burchard called the Democrats the party of “rum, Romanism, and rebellion.”

Romanism meant Catholics.

Blaine stood right there and said nothing.

Maybe he didn’t hear it. Maybe he wasn’t paying attention.

But the Irish Catholic voters he’d been courting heard it loud and clear.

Democrats printed the line on handbills and blanketed Catholic neighborhoods before Sunday Mass. Blaine lost New York by about 1,100 votes out of more than a million cast.

Lose New York, lose the presidency.

Grover Cleveland moved in. Three words did the job.

Kennedy’s Houston Gamble

John F. Kennedy faced the same Catholic suspicion in 1960, and he decided to meet it in the open.

He walked into a room full of Protestant ministers in Houston and told them where he stood.

“I believe in an America where the separation of church and state is absolute,” he said.

No bishop would tell him how to govern. No church would get special treatment.

He asked to be judged on his record, not his rosary.

It worked, barely.

Kennedy edged Richard Nixon in one of the closest elections in history.

That speech is still the gold standard for a candidate defusing a religious problem. Politicians have been borrowing from it ever since.

Jefferson the Godless Jacobin

Long before Catholics took the heat, Thomas Jefferson got branded a godless heretic.

The year was 1800, and the gloves were off.

Federalist preachers warned from the pulpit that a Jefferson presidency meant the end of Christianity in America.

One Connecticut paper predicted murder, robbery, and worse if he won.

In New England, the story goes, families hid their Bibles, certain Jefferson would come confiscate them.

He’d written about religious freedom, and his opponents twisted that into proof he had no faith at all.

Jefferson was no atheist. He believed in a Creator and admired the teachings of Jesus, even as he doubted the miracles.

He won anyway.

The Bibles stayed on the shelves, and the republic survived its first scorched-earth campaign.

Carter’s Playboy Confession

Jimmy Carter had the opposite problem. Voters in 1976 weren’t sure what to make of a candidate who talked about Jesus this openly.

A born-again Southern Baptist running for president was new territory.

The press treated his faith like a curiosity, poking at whether a man this devout could lead everybody.

Then Carter sat down with Playboy.

Trying to explain that he didn’t judge others, he admitted he’d “looked on a lot of women with lust” and “committed adultery in my heart many times.”

The point got lost.

The quote landed everywhere, Saturday Night Live ran with it, and Carter’s comfortable lead shrank in the final weeks.

He held on and beat Gerald Ford.

But a thoughtful answer about humility nearly torpedoed him two months before Election Day.

Romney’s Mormon Question

Mitt Romney spent two campaigns answering a question no other modern frontrunner faced: Are Mormons even Christian?

Polls in the 2000s showed more than a quarter of Americans wouldn’t vote for a member of the Church of Jesus Christ of Latter-day Saints.

Evangelical voters, the backbone of Republican primaries, held the deepest doubts.

In 2007, Romney borrowed Kennedy’s playbook.

He gave a “Faith in America” speech promising his church would never run his White House.

It didn’t save his first run.

He dropped out, and Mike Huckabee rode evangelical support past him in Iowa.

Romney came back in 2012 and won the nomination, the first Latter-day Saint to pull it off. Then he lost the general election to Barack Obama.

The Rumor That Wouldn’t Die

Barack Obama is a Christian. A stubborn slice of the country spent 2008 insisting otherwise.

A false rumor that he was secretly Muslim spread through forwarded emails and online forums, then jumped to cable news.

All through the campaign, polls showed around one in eight voters believed it, and the number barely budged no matter how often he corrected it.

Then came the other side of the coin.

Footage surfaced of his own pastor, Jeremiah Wright, shouting inflammatory lines from the pulpit of his Chicago church.

Suddenly, Obama was too Christian for some and not Christian enough for others.