Nowhere has it galvanized such large numbers as in Quebec, where many people still refer to themselves as pure laine, or pure wool, direct descendants of the 17th-century settlers of New France. The most emotional response has focused on conservative Muslim immigrants, who perhaps present the greatest contrast to traditional European-based culture and the secularism that Quebec struggled hard to win from the Roman Catholic Church.

The concerns are outsize by any measure. Muslims represent just 3 percent of Canada’s population, and while Islam is one of the fastest-growing religions in the country, Muslims will still account for less than 6 percent of the population in 2050, according to the Pew Research Center.

Nonetheless, Mr. Beaudry and his peers say they believe there is a real threat that Islamists are bending Canada’s tolerant culture to their will. The group’s main concern is political Islam pushed by the Muslim Brotherhood, the Pan-Arab movement that grew out of Egypt after the fall of the Ottoman Empire following World War I.

“Political Islam is slowly invading our institutions,” Mr. Beaudry declared, claiming that his group had documentary proof, though he was not prepared to show it. “We have to wake up people and shake them up, and then we will be able to bring change.”

The theme is popular among right-wing groups across North America and Europe, where the slow integration of conservative Muslim immigrants into Judeo-Christian cultures has excited fears among some of a global culture war.