Ms Blears said some of her views would be seen as controversial
People must be more willing to challenge ideas that conflict with core British values, the communities secretary has said.
Hazel Blears said there was too much "squeamishness" about condemning unacceptable practices, like forced marriages, for fear of causing offence.
Debate about the role of religion was "being sapped by a creeping over-sensitivity", she argued in a speech.
She also said it could be possible to engage with extremist groups.
However Ms Blears said negotiation could only be held with groups that did not advocate violence.
"Leaving the field clear" to such groups, rather than challenging their views and trying to change them, would undermine efforts to tackle extremist behaviour, she said in a speech at the London School of Economics.
Earlier, Ms Blears told the BBC that the "overwhelming majority" of people in Britain shared the same values and there must be a "dividing line" between those embracing and rejecting British "core values".
There were clear boundaries about what was acceptable in British society, the communities secretary said.
But people's fear of causing offence and consequent unwillingness to defend what was clearly reasonable and sensible had gone too far, she suggested.
Situations, for instance, where people were afraid to put up Christmas decorations because they believed they would offend different faiths or the recent case of a nurse - a practicing Christian - who was suspended after offering to pray for a patient flew in the face of common sense.
"The pendulum has swung too far," she argued.
"The quality of debate about religion in contemporary life - and by religion, I mean all faiths - is being sapped by a creeping over-sensitivity.
"At times leaders have been reluctant to challenge absolutely unacceptable behaviour - forced marriage, female genital mutilation or homophobia - because they are concerned about upsetting people's cultural sensitivities."
She added: "We would do well to be a little less anxious and a little more robust."
Engage, not isolate
Ms Blears called for the government to actively challenge the views and methods of those who shunned mainstream values, arguing that engagement was vital in rooting out extremism.
While stressing the UK could not talk to terrorist groups like al-Qaida, she said there was a strong argument for engaging with Islamic groups even if their support for democratic government, freedom of speech and gender equality was questionable.
"I know our political opponents will seek to make hay with this," she acknowledged, while stressing that talking to such groups did not mean one endorsed their views.
"They will say that somehow engaging with groups with extremist views shows a lack of proper understanding of them, that we are being hoodwinked, used or exploited by extremists.
"But if we leave the field clear to extremists, without any engagement at all, we embolden them and undermine our own objectives.
"And if we genuinely want to change minds, then we will never make progress merely by talking to people who already agree with us."
The government announced a range of measures last summer to try and check the influence of extremist groups in society.
These included support for the police and other bodies to identify and help people at risk of radicalisation and assistance for councils to launch programmes to "challenge and resist" extremism.