The religious symbol ban has been rebuked as an affront to Canadian values by many Canadians, and this week Toronto’s City Council followed Calgary’s example by calling for a national campaign to denounce the law. In Quebec, however, the law has become a powerful emblem of the province’s sovereignty over its own destiny. It is supported by about 66 percent of Quebecers.

Gérard Bouchard, a historian and sociologist with the University of Quebec at Chicoutimi, observed that the Bloc Québécois’s election success had laid bare that, while the Quebec independence movement was flagging, the nationalism of the past was not. Professor Bouchard knows a thing or two about the bloc, as his brother Lucien Bouchard founded the party in June 1991, before becoming premier of Quebec.

Professor Bouchard said that after the “non” camp won the referendums on Quebec’s separation in 1980 and 1995, English Canada had deluded itself into thinking that the challenge of a plucky, independent-minded Quebec was solved. The resurgence of the CAQ and the Bloc Quebecois, he said, showed otherwise.

“Both Blanchet and Legault are reaffirming a type of nationalism that had been dormant for decades but is coming back,” he said.

Even with the remarkable success of the bloc, Jean-Marc Léger, the chief executive of the Léger polling firm, said that its power was likely to be circumscribed in Ottawa, because Mr. Trudeau’s minority government would be able to get the 170 votes it needed to pass legislation by teaming up with the left-leaning New Democratic Party of Jagmeet Singh. That outcome, he said, would deprive Mr. Blanchet of holding the balance of power.

Nevertheless, Mr. Léger said the bloc’s surge reflected the extent to which Quebecers recoil when the rest of Canada tries to tell them what to do.

“Identity politics are still fertile ground in Quebec,” he said. “A majority of Quebecers aren’t satisfied with Quebec’s constitutional relationship with Canada and they want more economic and provincial powers. But they don’t want independence.”