David Cameron will announce plans to fast-track new powers to tackle radicalisation today as he declares Britain must confront " head-on the poisonous Islamist extremist ideology ".
The Prime Minister is expected to set out his intention to include a new counter-extremism bill in his Queen's Speech later this month as he chairs the first meeting of the National Security Council (NSC) since the Tories' election victory.
Planned measures include introducing new orders to ban extremist organisations and restrict people who seek to radicalise youngsters.
Mr Cameron will say: "For too long, we have been a passively tolerant society, saying to our citizens: as long as you obey the law, we will leave you alone.
"It's often meant we have stood neutral between different values. And that's helped foster a narrative of extremism and grievance.
"This Government will conclusively turn the page on this failed approach. As the party of one nation, we will govern as one nation, and bring our country together.
"That means actively promoting certain values. Freedom of speech. Freedom of worship. Democracy. The rule of law. Equal rights regardless of race, gender or sexuality.
"We must say to our citizens: this is what defines us as a society.
"To belong here is to believe in these things. And it means confronting head-on the poisonous Islamist extremist ideology. Whether they are violent in their means or not, we must make it impossible for the extremists to succeed."
The new package is expected to include:
::The introduction of banning orders for extremist organisations who use hate speech in public places, but whose activities fall short of proscription.
:: New Extremism Disruption Orders to restrict people who seek to radicalise young people;
:: Powers to close premises where extremists seek to influence others;
:: Strengthening the powers of the Charity Commission to root out charities who misappropriate funds towards extremism and terrorism;
:: Further immigration restrictions on extremists;
:: A strengthened role for Ofcom to take action against channels which broadcast extremist content.
The plans are part of a broad strategy to tackle extremism set out by Home Secretary Theresa May earlier this year.
Mrs May will tell the NSC - a forum where the Government's objectives for national security are discussed by ministers - that "the twisted narrative of extremism cannot be ignored or wished away".
"This Government will challenge those who seek to spread hatred and intolerance by forming a new partnership of every single person and organisation in this country who wants to defeat the extremism," she will say.
"We will introduce legislation to combat groups and individuals who reject our values and promote messages of hate.
"We will empower institutions to stand up against the extremists and challenge bigotry and ignorance. And we will support those who are fighting back against extremism online.
"United by our values and the basic principles of our society we are determined to defeat extremism in all its forms."
The terror threat level was raised from substantial to severe in August in the face of Islamic State's activities in Syria and Iraq.
Ministers responded to the threat by introducing a new Counter-terrorism and Security Bill.
The legislation included new orders that can block alleged British fighters from returning to the UK and gave police powers to seize the passports of those suspected of plotting to travel abroad to join the fighting.
The Government is also expected to revive controversial plans for new laws governing the retention of people's activities on the internet and social media.
In 2013, the Communications Data Bill - labelled a "snoopers' charter" by critics - was shelved after opposition from the Deputy Prime Minister Nick Clegg and the Liberal Democrats.
Mrs May made clear that the new measures would target not only Islamist groups, but also extremists of other kinds, including neo-Nazis.
The Home Secretary told ITV1's Good Morning Britain: "This is a great country to live in, we have a pluralistic society, we are one nation living together. But sadly, there are those who seek to divide us - the extremists of all kinds.
"There's Islamist extremism, neo-Nazi extremism, trying to preach hatred and intolerance and challenge the values that underpin our society - values of democracy, tolerance, freedom, the rule of law.
"What we want to do is ensure that those who are trying to promote that hatred and intolerance, we can deal with them."
Asked whether the proposed measures were counter to the principles of free speech, Mrs May said: "No they are not. This is a difficult area and it is an area where we do have to be careful about how we draft the legislation to make sure that it does cover what we want it to cover, but still enables free speech to take place.
"This isn't an easy measure to bring in, it is something that has to be looked at very carefully. We are very conscious of the need to still maintain that value of free speech."
Asked whether the Conservative-only Government had been "unleashed" to take more radical action in this area by the absence of its former Liberal Democrat coalition partners, Mrs May said: "I think we are all welcoming the fact that we can be a majority government.
"The British people have given us that trust, that we can go forward, that we can show we are a party in government that can't just run the economy well and be competent, but also obviously has a care for social justice, wants to defend the values that underpin our society and wants to deal with those who are trying to preach and promote this hatred and intolerance and seeking to divide us.
"We are one nation, we will be governing for one nation and as one nation."