Duncan Morrow, who heads a group advising Holyrood ministers on how to tackle the problem, also says sectarianism has gone beyond religious bigotry and is characterised by an "us and them" culture, with people defining themselves against others.
In his first interview since taking up the post, Mr Morrow said his panel was not restricted by legal definitions of the problem, claiming political, social, historic and cultural factors were as much a part of bigotry as religious faith.
He also said a striking aspect of the country's sectarianism was the frequent claims of "an embedded anti-Catholicism that isn't going away in Scotland".
His views will clash with many in Scotland who believe that unless there is an explicit reference to another's faith, insults, derogatory terms and even songs in support of paramilitary organisations are not sectarian.
Court cases involving either Ulster Loyalist or Irish Republican songs have seen the sectarian element disregarded because of an absence of reference to faiths.
Mr Morrow, who has for a decade chaired the Community Relations Council, which promotes cultural and religious diversity in Northern Ireland, said: "It has been said to us at various times that there is still in Scotland a habit of excluding people from social circles where the real decisions are taken, and that continues to be a real issue. It's not just a ned issue.
"You can't take religion out of it but certainly it's not just about religion. It's about everything which has flowed from religion in the past and where religion has been used as a reason to exclude or discriminate against.
"There's a sense of us and them, a sense of difference which may not always be positive and people defining themselves against other people."
Mr Morrow, a lecturer at the University of Ulster's School of Criminology, Politics and Social Policy, insists issues in Scotland are markedly different to Northern Ireland, and comparisons are limited.
The group's members include Michael Rosie, a sceptic on sectarianism being a major issue in Scottish society. It will provide the evidence to advise ministers on the impact of bigotry and what potential improvements could be made.
It has already commissioned a report into the impact of parades.
Mr Morrow said Scotland had to confront a culture of denial about the existence of centuries-old sectarianism, adding that it creates a nervousness when discussed.
But he warned against a culture of victimhood, of making sectarian allegations without evidence. He advocated a form of debate that avoided falling into finger-pointing and blame.
He said: "One very obvious element to this which is quintessentially Scottish is the habit of not talking about this.
"For something which people say doesn't exist and you don't need to talk about, they are very nervous of you pulling up the stones and looking underneath them."
Mr Morrow added: "Scotland has managed this in some ways by a very judicious not talking about it. Coming from Belfast where it is so upfront and in your
face that's striking.There's a sense in some circles of an anti-Catholicism which continues to operate to exclude people. We have to find different ways to discuss the range of experiences from each extreme and the bit in between.
"That includes those who say it's something which doesn't exist outside football and 'I never encounter it' to others who say it's a much deeper pattern of how Scottish society works. If sectarianism is a real thing affecting real people there are legitimate ends of government and public policy that need to be looked at.
"On the other hand, if people start to live out a victimhood that doesn't help particularly either. What's not good enough is to just make allegations."
Community safety minister Roseanna Cunningham said: "The work being carried forward by Duncan Morrow and the sectarianism advisory group to gather evidence on the nature of sectarianism and the impact and effectiveness of the different approaches being taken will help us gain a broader understanding of the problem in Scotland.
"We will use this evidence to make sure that future measures to tackle the issue are evidence-based."