Trevor Phillips forecast conflict between communities and the undermining of Britainâ€™s rights and values unless the country abandoned past â€œsqueamishness, complacency and liberal self-delusionâ€ about the problems which racial, religious and cultural differences can produce.
His recommended steps include ensuring English is the standard working language, requiring public bodies to promote integration and curbing limits on free speech.
His rallying cry is part of a pamphlet, Race and Faith: The Deafening Silence, published today by the thinktank Civitas.
The writer and TV producer, a former chairman of the Equality and Human Rights Commission, argued that Britain is living in a new era of â€œsuperdiversityâ€ with different groups of people arriving in greater numbers than ever before.
This required a shift from Britainâ€™s traditional approach of gradual and natural integration to a more active policy.
He wrote: â€œIn my view, squeamishness about addressing diversity and its discontents risks allowing our country to sleepwalk to a catastrophe that will set community against community, endorse sexist aggression, suppress freedom of expression, reverse hard-won civil liberties, and undermine the liberal democracy that has served this country so well for so long.
â€œWorst of all it may destroy popular support for the values that have, in my opinion, characterised the greatest political advances in my lifetime: equality and solidarity.â€