Even in death, they don't want to be together. In Belfast City Cemetery, an underground wall separates the Catholic and Protestant dead. Sectarian division exists from the cradle to the grave.
Catholic and Protestant children go to different schools and live in different areas. When they grow up, only a minority work in districts dominated by the 'other' religion. The peace process was meant to bring a transformation. While the murder rate has fallen, little else has changed.
"Belfast is far from being the post-conflict city dreamed of by planners, investors and British and Irish politicians," says University of Ulster lecturer, Pete Shirlow, co-author of a new book which discloses the naked sectarianism that still resides in the North.
In North Belfast alone, there were 6623 sectarian incidents from 1996 to 2004. Shirlow's research exposes deep divisions there. Upper (Protestant) Ardoyne contains no shops. There are six grocers in Lower (Catholic) Ardoyne. Less than one in five Protestants will use them. Eighty-two per cent of Catholics refuse to use the leisure centre in Protestant Ardoyne.
An Ardoyne Protestant says of his neighbours across the peaceline: "I would love to burn those bastards out. The soap dodgers (derogatory name for Catholics) breed like rabbits. All you ever hear from them is whinge, whinge, whinge. Why don't they get jobs and live like decent people?" Another says: "If I knew my neighbour was shopping in Fenianville, I'd take a pounder (hammer) and knock his head of his shoulders."
One Ardoyne Protestant who shops in west Belfast has to hide such 'disloyalty': "We shop in Curley's. It's so cheap and who is going to know we are Prods? But we take Tesco bags with us and put the shopping in them before we go home. If I walked up that path with Curley's bags I'd get my windies (put) in."
An Ardoyne Catholic says: "One of my neighbours bought a suite of furniture from a place in the Shankill. I told him I wouldn't be in his house as long as that furniture was there. He was giving money to people who (had) attacked us."
Shirlow found much of his research depressing: "You'd see a playground on one side of the fence, and it was out of bounds for the kids on the other side of the fence. Generation after generation is growing up like this."
Rather than challenging division, the peace process is about managing it, he says. At the time of the Belfast Agreement, both sides were told they'd won. Instability over the North's constitutional future, and continuing inter-community conflict, was inevitable. There's been a growth in attacks on symbols of tradition such as Orange Halls, GAA clubs, and churches.
In some Belfast communities, three-quarters of people refuse to use their closest health centre if it's in an area dominated by the other community. Such attitudes are understandable. A third of all victims killed in Belfast were murdered in their homes or metres from their homes. This war was very personal.
Although they could still be strongly nationalist or unionist, pensioners with experience of pre-1969 society held less sectarian attitudes than younger people.
They were more likely to say, 'I come from Belfast'. The younger generation, steeped in parochialism, were more likely to say, 'I come from West Belfast' or 'I come from East Belfast'.
Only 11% of Catholics and 7% of Protestants live in religiously mixed areas. Graffiti such as 'KAT' (Kill All Taigs) or KAH (Kill All Huns) is common in flashpoint areas. Recently, there have been efforts to camouflage peacelines through landscaping. They're hidden by parkland or industrial buffer zones. Shirlow finds "attempting to normalise the abnormal is absolutely bizarre".
Catholics working for mainly Protestant firms tend to be safer if they're not on the shop-floor. A personnel manager says: "The worst thing that could happen in the offices is that someone would throw a bagel at you. On the shop floor, you could get a spanner in the teeth."
In the religiously mixed, middle-class Carryduff area of south Belfast, residents were less likely to vote DUP or Sinn Féin. But there were interesting social differences there. Three-quarters of Catholics, compared to only half of Protestants, went out for a drink; 60% of Catholics but only 45% of Protestants went to the cinema.
Although they disagreed on nationality, both sides in Carryduff were united in the belief they'd picked a great place to live because house prices there were sure to rise.
During the conflict, 78% of civilians killed in Belfast died in the north or west of the city. More prosperous south and east Belfast endured minimal violence.
Shirlow says Belfast has undoubtedly become "more chic" in recent years with the development of luxury apartments, business premises, restaurants, and bars.
"But it's those who suffered the least in the conflict the middle-classes who are benefiting the most from this. Those who suffered the most the Catholic and Protestant working-class are benefiting the least. The irony is that, if they came together, they'd access far more than by standing separately."
Belfast: Segregation, Violence and the City, Peter Shirlow and Brendan Murtagh, Pluto Press.