Britain needs a stronger sense of national identity, Conservative leader Michael Howard has told the BBC.
"We should be British first and British last, while staunchly adhering to our respective faiths," Mr Howard said.
"You have to have allegiance to our values and the British way of life," the Conservative leader added.
Mr Howard is calling for wider use of powers to revoke the citizenship of foreign nationals seen as a threat to national security.
Mr Howard told BBC Radio 4's Today programme: "We must build on and strengthen our shared sense of Britishness while recognising it is not incompatible with a continuing attachment to other traditions."
He said the government must more often use its powers to remove people whose presence would be prejudicial to the national interest.
"There are people, as we have seen recently, who are fundamentally hostile to the values of this country and who could constitute a threat to our national security.
"The government, perhaps belatedly, looks as if it is beginning to take some action in respect of some of those people.
"The powers are there. I think they should be used more robustly."
He added: "If we can establish this strong sense of shared British identity it will fill the void that to some extent exists, which is often filled by philosophies and views that are utterly alien to our society, which breed hatred of our society and which ultimately lead to the kind of catastrophe we saw on 7 July."
He said that multiculturalism was "not a very helpful word to use because it means so many things to different people".
But he added: "What we all want is a strong British identity which we share."
Mr Howard's words come after 10 foreign nationals deemed a threat to Britain's security were detained pending deportation.
Writing earlier in the Guardian newspaper, Mr Howard, who is the son of immigrant parents, said British values included tolerance, decency and a sense of fair play.
He said it used to be "taboo" to question UK society's record on integrating people of different colours, creeds and backgrounds.
But "that complacency was shattered" by the 7 July attacks, he wrote.
His comments come two weeks after shadow home secretary David Davis called on the government to scrap its "outdated" policy of multiculturalism.
Tony Blair later said he did not know what multiculturalism really meant - and a BBC survey last week suggested many Britons shared his confusion.