By Gerald F. Seib | The Wall street Journal

It’s an article of faith in diplomacy that every crisis also carries the seeds of opportunity. So it is with the Charlie Hebdo tragedy in France: It represents a chance to change the global attitude toward what can only be described as a rising tide of extremism and intolerance.

Which is why the failure of the Obama White House to send a high-level representative to Sunday’s international march of solidarity in Paris represented such a lost opportunity—a mistake the White House acknowledged Monday. Few nations have more at stake in stemming this rising tide than does the U.S.

The attack that killed 12 at a satirical magazine in France is most often described as an act of terrorism, which it certainly was, as was the follow-on siege at a kosher supermarket that left another four dead.

But those attacks also represent something more. They are merely the most graphic display of a new global plague of violence perpetrated against those with whom you disagree. Indeed, France’s experience shows that the whole idea of multiculturalism is undergoing a stress test.

The idea of savagely attacking those who don’t share your beliefs lies at the core of both the Islamic State movement and al Qaeda in the Arabian Peninsula. In Iraq, the hope that Sunnis, Shiites and Kurds can live together in a multisectarian state is under sustained assault. As the forces of Islamic extremism take hold more broadly, women in particular are being persecuted across a swath of the developing world.

At the same time, Christians are being widely persecuted simply for being Christians, and not just in land controlled by Islamic State fanatics. Open Doors, an organization that aids persecuted Christians, says 2014 brought “the highest level of global persecution of Christians in the modern era,” but warns that this year could be worse.

More than 70% of Iraq’s Christians have fled since 2003, Open Doors estimates. More than 700,000 Christians have left Syria since the civil war there began in 2011. Africa has become equally hostile terrain for Christians. In North Korea, an estimated 70,000 Christians are in prison because of their faith.

Meantime, journalists who shine a light on such practices are under attack. The journalists of Charlie Hedbo were targeted directly by the propaganda machine of al Qaeda in the Arabian Peninsula because they dared to publish cartoons deemed offensive.

But the plague is much wider. The Committee to Protect Journalists has identified 221 journalists who were jailed in 2014, the second-highest tally since it began tracking that sad statistic in 1990. The guilty countries range from China to Myanmar to Egypt. In Iran, Washington Post reporter Jason Rezaian has been held in Tehran’s Evin Prison for more than 170 days on vague and trumped-up charges he can’t fully comprehend because he has been denied access to a lawyer.

Another 27 journalists were simply murdered in the line of duty last year, the committee says.

Global outrage at such behavior has been insufficient. That may have started to change in a big way over the weekend in Paris. A million people filled the streets to march against the threat of Islamic extremism. More than 40 presidents and prime ministers showed up to lend their names and faces to the movement. Newspapers around the world showed remarkable pictures of the Israeli prime minister and the Palestinian president sharing space in the front row of leaders, arms linked, marching through the streets.

Other nations in turn showed their true and contrasting colors. China’s state-controlled news agency responded to the Paris attacks with a commentary saying the tragedy shows that there should be limits placed on freedom of the press. As the world stood up for freedom of expression, Saudi Arabia over the weekend instead publicly flogged a blogger simply for being a blogger.

Amid that picture, the lack of a high-level American leader in the streets of Paris means this global picture wasn’t filled out properly. The U.S. has sacrificed civilians and more soldiers than anybody in the fight against extremism and for religious and cultural tolerance. America itself is the ultimate melting pot, where the Islamic population is expected to grow to 6.2 million in 2030 from 2.6 million in 2010, according to the Pew Research Center. Any new global movement toward tolerance needs an American face.

White House officials agreed Monday they should have provided that face. “It’s fair to say we should have sent someone with a higher profile,” said press secretary Josh Earnest. President Barack Obama would have liked to have attended himself, he said, though officials worried about the security complications of a presidential trip. But he said someone other than the U.S. ambassador to Frances should have attended.

The White House will come back next month by hosting a summit on countering violent extremism. Meantime, even more important is the way leaders in the Muslim world respond to their threat from within.

“In a sense France was not attacked because it was France, but because it was a democracy,” Gerard Araud, France’s ambassador to the U.S., said in an interview. “If all the heads of state and government went to Paris, they did so because they felt it was not a French story.”

Corrections & Amplifications

An earlier version of this column misspelled the name of Charlie Hebdo, a satirical French magazine.