Prejudice against Muslims has "passed the dinner-table test" and become socially acceptable in the UK, a senior Conservative is to say.
Baroness Warsi, co-chairman of the Tory Party, will warn against dividing Muslims into moderates and extremists.
The baroness, the first Muslim woman to serve in the cabinet, will say such labels fuel misunderstanding.
She will use a speech at Leicester University to accuse the media of superficial discussion of Islam.
Baroness Warsi will say anti-Muslim prejudice is now seen by many Britons as normal and uncontroversial, and she will use her position to fight an "ongoing battle against bigotry".
In extracts of the speech, published in the Daily Telegraph, the peer blames "the patronising, superficial way faith is discussed in certain quarters, including the media", for making Britain a less tolerant place for believers.
She is expected to reveal that she raised the issue of Islamophobia with Pope Benedict XVI during his visit to Britain last year, urging him to "create a better understanding between Europe and its Muslim citizens".
The BBC's religious affairs correspondent Robert Pigott said Baroness Warsi is to say publicly what many Muslims privately complain about - that prejudice against them does not attract the social stigma attached to prejudice against other religious and ethnic groups.
"Lady Warsi has broached the issue before," Robert Pigott says.
"She told the 2009 Conservative Party conference that anti-Muslim hatred had become Britain's last socially acceptable form of bigotry, and claimed in a magazine article last October that taking a pop at the Muslim community in the media sold papers and didn't really matter."
In her speech, she is expected to say the description of Muslims as either moderate or extremist encourages false assumptions.
"It's not a big leap of imagination to predict where the talk of 'moderate' Muslims leads; in the factory, where they've just hired a Muslim worker, the boss says to his employees: 'Not to worry, he's only fairly Muslim'," she will say.
"In the school, the kids say: 'The family next door are Muslim but they're not too bad'.
"And in the road, as a woman walks past wearing a burka, the passers-by think: 'That woman's either oppressed or is making a political statement'."
Baroness Warsi will say terror offences committed by a small number of Muslims should not be used to condemn all who follow Islam.
But she will also urge Muslim communities to be clearer about their rejection of those who resort to violent acts.
"Those who commit criminal acts of terrorism in our country need to be dealt with not just by the full force of the law," she will say.
"They also should face social rejection and alienation across society and their acts must not be used as an opportunity to tar all Muslims."
Asked about Baroness Warsi's speech, a No 10 spokesman said she was expressing the view that there needed to be a debate "about the issue of radicalisation in Great Britain and terrorism".