Their concerns about immigration and perceptions that Islam is challenging prevailing national values are widely shared, both among some Norwegians on the left of the political spectrum, and among many on the right, who in September put the Conservative Party into office after eight years of government by Labor Party-led leftist coalitions.

In a nation that has long prided itself on its liberal sensibilities, the intensifying debate about immigration and its effects on national identity and the country’s social welfare system has been jarring — and has been focused on the anti-immigration Progress Party, which is part of the new Conservative-led government.

The Progress Party came under intense scrutiny in 2011, when a former member, a Norwegian named Anders Behring Breivik, bombed government buildings in Oslo, killing eight people. He then killed 69 more people, mostly teenagers, in a mass shooting at a Labor Party summer camp on the island of Utoya. Mr. Breivik, who was convicted of mass murder and terrorism, had been a member of the Progress Party, attracted by its anti-Islamic slant, from 1999 until he was removed from the rolls in 2006 for not paying dues, having quit the party because it was not radical enough.

Still, the performance of the Progress Party in the first general elections since the Utoya massacre and its success in winning a place in government have raised some eyebrows; quite unfairly, Ketil Solvik-Olsen, minister of transportation and communication and a deputy leader of the party, said in an interview.

Mr. Solvik-Olsen recently discussed politics and faith at the Norwegian Lutheran church in Mortensrud. A tall, cheery man of 41, educated in Ohio and once employed by Disney, Mr. Solvik-Olsen scoffed at the notion that the party had anything to do with Mr. Breivik. “He left because his ideas were not getting support,” he said. “We are strict on immigration, but this is not a war on cultures. Our idea is to protect our welfare system.”