Once the clerical party of the monarchy, the right in France stood as a staunch defender of the Church and opposed the secularism of the French Revolution. Broadly speaking, it remained hostile to what it perceived as the left’s excess of zeal in implementing secularism, or laïcité, and this skepticism survived until World War II, after which the right began using secularism as a shield against the increasing size and importance of Islam in France.

Today, the right has defined itself largely with regard to economic and security issues—like labor reform and strong defense. But it has been torn apart from the inside between those who have argued for a strict interpretation of French secularism and those who approach the debate more flexibly. Its mainstream party, the Union for a Popular Movement (UMP), went through an internal crisis in 2015 and was renamed The Republicans, in what was widely seen as a PR move. It’s no longer clear what the right stands for, and it has suffered as a result: During the legislative elections of 2017, the right-wing coalition got its worst score in the history of the Fifth Republic.

The left is also struggling to define what it stands for. Characterized by radical social-justice activism in the 1960s and 70s, the left—except at the fringes—now loosely stands for the ideals of liberalism, that is, emphasizing individual responsibility over government intervention. (With the important caveat that in Europe, in contrast to the United States, a base level of government intervention that might be considered radical in America—including universal health care and strong labor protections—is taken for granted.) But even this modest program doesn’t enjoy the support of all its members. Republican leftists—those who identify with the rigidly secular history of the Fifth Republic—feel at odds with more “radical” leftists, who adhere to a more American approach toward religion and multiculturalism, with its emphasis on freedom of religion. One part of the French left believes that the state should offer protection from religion, and the other, protection of religion.

“There is an important … divide around Islam in France, and between people who are, in the name of a certain brand of secularism, open to Islam, and others who, in the name of another secularism, are very closed off to Islam,” said Pierre Bréchon, a professor of political science at Sciences Po Grenoble. “This debate goes beyond the left/right divide.”

In fact, the issue of Islam in France is “breaking” the left, according to Benjamin Haddad, a research fellow at the Hudson Institute. This is not just for ideological reasons, but for practical ones as well, he says: Local elected officials have long leveraged identity politics to win elections, but now the strategy is backfiring. Christophe Barbier, a journalist and author of The Final Days of the Left, put it this way: “If the left continues on this path, it will provoke a major ideological confrontation that will precipitate its defeat, because there will always be more people in this country that will react vindictively and aggressively toward immigrants, and especially Muslims, rather than risking a bet on community-building.”