The Republican Party is considering repealing the 11th Commandment.

The first 10 came from the Book of Exodus, and were greeted by what the Bible described as “the thunderings, the lightning flashes, the sound of the trumpet, and the mountain smoking.” The 11th Commandment — Thou shalt not speak ill of any fellow Republican — became gospel after a speech Ronald Reagan gave in the Lafayette Hotel in Long Beach, California, on April 1, 1967. That, too, was greeted with thunderous applause, though there were no reports of lightning flashes or mountain smoking. Those would not hit California until decades later.

But the Reagan ethos expressed before the California Republican Assembly — the sounding of a trumpet, politically at least — helped account for Republican victories in seven of the 10 presidential races that followed, which we sometimes forget is a record roughly comparable to the power of the New Deal coalition beginning in 1932.

“The Republican Party, both in this state and nationally, is a broad party,” said Reagan in his first year as governor of California and already spoken of as a future president. “There is room in our tent for many views; indeed, the divergence of views is one of our strengths. Let no one, however, interpret this to mean compromise of basic philosophy or that we will be all things to all people for political expediency.”

That speech was more than a half-century ago, and it occurred during the week when The Beatles posed with wax figures from Madame Tussauds for the cover of their “Sgt. Pepper’s Lonely Hearts Club Band” album and when Jimi Hendrix set his guitar on fire for the first time. (He was hospitalized for burns.)

Today, the “big tent” philosophy growing out of the Reagan nostrum, expressed many times but seldom as succinctly or as forcefully as in that early speech, is under attack as never before. The House Freedom Caucus is agitating to expel Reps. Liz Cheney of Wyoming and Adam Kinzinger of Illinois — the only two Republicans who agreed to join the House committee investigating the insurrection at the Capitol in January — from the party.

This move comes two months after a Quinnipiac University national poll showed that 85% of Republicans said they prefer political candidates who mostly agree with former President Donald J. Trump. A majority of Americans expressed a preference for candidates who mostly disagree with Trump.

In truth, the two representatives mostly agree with Trump, and voted that way. Cheney sided with the president 93% of the time, higher than New York lawmaker Rep. Elise Stefanik, who replaced her as House Republican Conference chair after recording a 78% Trump loyalty record. Kinzinger voted with Trump 99% of the time in his first two years, though his record dropped to a still robust 84% in the second half of the Trump term.

The move to eject the two from the GOP conference and perhaps threaten their committee assignments is being led by Rep. Andy Biggs of Arizona, who argues that the two agreed to “join the Democrats on a witch hunt” against members of their own party. He characterized them as “two spies”; they are among the 10 Republicans who voted to convict Trump in the second round of impeachment.

Party purges rarely succeed. The most famous effort was undertaken by Franklin D. Roosevelt, who, in trying to convert the Democrats into a liberal party in 1938, targeted Democratic Sens. Walter George of Georgia, Ellison “Cotton Ed” Smith of South Carolina, Millard Tydings of Maryland and Guy Gillette of Iowa, all of whom prevailed anyway. The only party purge in modern times that succeeded was undertaken during World War I by Woodrow Wilson, who employed what he called an “acid test” of loyalty, used mostly against fellow Southerners, “thereby,” according to biographer John Milton Cooper Jr., “muffling charges of outside interference.”

But overall, that has not been the way either party has proceeded, and certainly it is not the Reagan formula. In 1986, the Republicans nominated Rep. Ed Zschau, who had a relatively low rating from the American Conservative Union (46 out of 100), for the Senate. The weekend before the election, Reagan praised Zschau at a Republican event, saying, “Here in California, we’re lucky to have a standard-bearer who personifies enterprise and creativity, a candidate who young people can identify with and who can lead this party and our country into the 21st century.”

Zschau lost, but Reagan’s “big tent” concept endured. Republicans rarely have broken the 11th Commandment, conceived by California GOP chairman Gaylord Parkinson but popularized by Reagan. Here, from that 1967 Long Beach speech, is the essence of the Reagan ethos:

Within our tent, there will be many arguments and divisions over approach and method and even those we choose to implement our philosophy. Seldom, if ever, will we raise a cheer signifying unanimous approval of the decisions reached.

Reagan urged party unity and party discipline. But he also argued that “unity does not require unanimity of thought.”

Today’s Republicans are in one of their periodic struggles for the soul of their grand old party. It happened in 1952, when Dwight Eisenhower faced Sen. Robert Taft of Ohio, and in 1964, when Sen. Barry Goldwater of Arizona faced Gov. Nelson Rockefeller of New York, and in 1976, when Reagan sought to unseat President Gerald Ford. But throughout these struggles, the former Democrat and New Dealer, who in 1980 would win the White House, hewed to his views about how Republicans should treat each other.

Trump is the most significant, and most powerful, Republican figure since Reagan. The 45th president seldom spoke about the 40th, but Reagan anticipated the rise of a Trump-like figure.

“Our 11th Commandment,” Reagan said in 1967, “is perhaps more profound than we realize.” More profound, perhaps — but more endangered than he might have imagined.