Home Secretary Charles Clarke has said he is "shocked" the suspected London suicide bombers were British-born.
Mr Clarke says the attacks are a challenge for faith leaders
Mr Clarke said the attacks were a "clarion call" for everybody in the UK to defend their society rather than assume "we are all OK".
The Muslim community especially must "stand out" against the ideology which promotes bombings, he told BBC News.
He said he would consider all means necessary - including deportation - against those fomenting terrorism.
Speaking ahead of an emergency EU summit about security measures in Brussels, Mr Clarke said it was "a central hypothesis" that the bombers were part of a wider network.
Mr Clarke said there were organisations who wanted to destroy the fundamental structure of UK democracy.
"I think that is the clarion call to us, to us as politicians, as broadcasters, to faith leaders, to lawyers, to everybody, to say we have to fight for this society we have, rather than just coasting along and assuming it's all OK."
Mr Clarke said the right balance was needed between civil liberties and security.
The belief that "home-grown terrorism" was to blame for the bombings means intelligence must be improved, despite the "first class" job done by the police and security services, he said.
Ready for more attacks?
During the EU talks in Brussels, Mr Clarke will push for European agencies to share more intelligence information.
But he argued the anti-terror strategy had to address the fact that ideology, not poverty, was the driving force behind such attacks.
"It's ensuring that the whole of the Muslim community, supported by the whole of the society, stands out against this sort of belief."
Mr Clarke said he was encouraged by the Muslim community's response.
He said he was looking directly at people who "preach hatred", with deportation one option.
The home secretary said the UK had to assume other people were prepared to carry out attacks.
Intelligence had to be at the centre of addressing that problem, he argued.
Former Metropolitan Police chief Lord Stevens has suggested that three thousand people, who are now in Britain have trained in al-Qaeda camps.
Mr Clarke said he did not accept that figure but a "large number" of people had attended such camps.
"But only a very few come to this cataclysmic decision that those four individuals did on Thursday," he added.
Tony Blair on Wednesday met a delegation of Muslim MPs to discuss the discovery of the suspected bombers.
The Muslim Council of Britain says it reacted with "anguish, shock and horror" to news that British-born Islamic youths were involved in the attacks.
The council's secretary-general, Sir Iqbal Sacranie, said: "Nothing in Islam can ever justify the evil actions of the bombers."
Shahid Malik, whose Dewsbury constituency was the scene of police raids in the bombing investigation, said the Muslim community faced a "massive wake-up call".
He told BBC News after his meeting with Mr Blair: "The challenge is straightforward - that those voices that we have tolerated will no longer be tolerated, whether they be on the streets, in the schools, in the youth clubs, in a mosque, in a corner, in a house.
"We need to go beyond condemning - we need to confront."