James MacMillan launched an attack on what he claimed was "endemic" anti-Catholicism and said the bigotry was holding back progress in making Scotland a multicultural society able to accept people from different backgrounds.
"For me, one of the major cancers in society is the lingering and sleepwalking bigotry that many in Scotland feel about Catholics, which has huge implications for a pluralistic democracy," he said.
"It is in the media, politics, debates about education, sports and the professions. Traditional anti-Catholic phobias and paranoias have even gained us infamy abroad. There is no way that the Catholic experience in Scotland is ready to be celebrated as it should be."
Mr MacMillan, who at 40 is acknowledged as Scotland's leading younger composer, was speaking before delivering his lecture at the Edinburgh Festival later today. He has chosen to use the talk, Scotland's Shame, to tackle the "second nature" bigotry.
Last night Father Tom Connelly, a spokesman for the Scottish Catholic Church, backed Mr MacMillan's comments and said he was a brave man for making them. "My experience is that Scottish people hate to be labelled as bigots. Anti-Catholicism has been part and parcel of Scotland for years, but I for one had hoped it had disappeared," he said.
In his lecture, Mr MacMillan will discuss the resignation of Donald Findlay QC as vice-chairman of Glasgow Rangers after he was reported to have been singing sectarian songs at a party.
As a family man and a practising Catholic with a knowledge of both football and politics - he is a former communist and a Celtic supporter - Mr MacMillan said he was in a unique position to open up a debate.
His children, who attend their local Catholic school, were threatened by an anti-Catholic schools lobby and the sectarian nature of football.
"I am a public figure not normally associated with this question and the fact that I am not a priest might have some currency in this debate," he said.
"There are 800,000 Catholics in this country - 250,000 practising. To have them sidelined and trivialised is outrageous."Reuse content