In death, Nelson Mandela has become something of a deity

The T-shirts are flying off the shelves in upmarket Sandton, and the mugs, bracelets and ostrich eggs bearing His likeness. There is no need to say who He is, of course. In death, Nelson Mandela has become something that in life he would abhor, a kind of deity, whose motives and achievements are now beyond question.

They worship him in this rich, air-conditioned offshoot of Johannesburg, built to provide a haven from endemic crime. And in Kliptown, a shanty district of Soweto that can plausibly claim to be the worst human settlement on earth. They worship him around the world, too. No American president bothered to turn up to the funeral of Margaret Thatcher earlier this year but Mandela, once spurned by the Iron Lady as a communist subversive, gets three, including the incumbent. George W Bush, Bill Clinton and Barack Obama will be there, by that flag-draped coffin, basking in the reflected glow of "Tata", the nation's "grandfather". Mandela was - is - a star, one of effortless pulling power.

"It's a way of honouring him," says Salo Mathen, as he scoops up two Mandela shirts from the counter. You can buy shirts decorated with Mandela's handprint or one sporting his prisoner number during years of internal exile on Robben Island, 46664. A nearby gallery is doing a fine trade in Mandelarana. The great man's likeness has always worked well in pop art, especially when simplified in black and white, like Che Guevara's. "We've always been selling Mandela things but suddenly people were coming in and asking for Mandela-this, Mandela-that," says the sales assistant.

Over in Soweto, that vast, sprawling city created to place blacks at a safe distance from the whites who exploited them, candles burn in an impromptu shrine. "Hamba kahle Madiba" are the words in Zulu adorning the portrait of the lost leader - "Go well, Madiba". Madiba is the clan name of South Africa's first black president, elected in 1994 after a personal struggle against apartheid that cost him nearly three decades of freedom. Thabang Mosar plays his nation's anthem on a battered recorder and reflects on the achievement of his dead leader. "If it wasn't for Mandela, I wouldn't be here," he says.

"I would have had to fight for my freedom and probably die. He won our freedom by talking, by forgiving." British politicians can only dream of the reverence accorded to this Xhosa son of the Transkei. Mandela's dedication to his cause, his epic confinement, deserves no less. But his exalted state owes something to timing. Mandela served one term as president, preferring the role of elder statesman, to hands-on chief executive. That early departure distanced him from the failures of the Rainbow Republic, now clearly visible.

The disparity in wealth in South Africa is glaring, squalor on an epic scale coexisting with manicured suburban affluence. A quarter of working-age South Africans are unemployed, a 10th of the country can't read and a fifth of people aged between 15 and 49 are infected with HIV. That shrine in Soweto stands next to a table-like monument inscribed with the words of a declaration made in 1955 by the leaders South Africa's black liberation movement. It promised much: equality between races, freedom of movement and decent housing. Almost 20 years of majority rule has done little for Kliptown, where housing is of the improvised variety - shacks constructed from old advertising billboards and whatever else its desperately poor inhabitants had to hand.

Raw sewage runs in a gully between these mean dwellings. There are chemical lavatories, provided by the government, but only one per 40 or so inhabitants. Electricity is stolen from street lights. Gangs hang around in search of a victim, fuelled by alcohol and a new kind of drug, ARV, derived from crushed anti-HIV pills and then smoked. A display of wealth here would be a death sentence.

Still, there is nothing but admiration for the man who, wittingly or not, authored a one-party state. "Nelson Mandela is the world," says Nocuzola Dyamora, who lives with 11 other members of her family, six adults and six children, in a two-room shack. The adults share two beds and the children sleep on the floor. Light shines through the gaps in the corrugated iron roof. Nocuzola has known nothing else in her life but remains optimistic. Life, she believes, will get better.

The government is building houses and she and her sisters might be granted one. Meanwhile, Jacob Zuma, president of South Africa, is accused of spending lavishly on his personal residence. The ruling ANC is mired in allegations of corruption but is going nowhere - there is no effective opposition in South Africa. The national celebration of Mandela's life that will consume the country this week is a welcome distraction.

"My assessment of where we are today is that [Mandela's] legacy has been betrayed by our failure as a society to live the ideals - of South Africa governed by clean, competent and accountable leadership - but instead by leadership that is focused on surviving, enriching and advantaging itself," says Mamphela Ramphele, a former girlfriend of Steve Biko, the Black Consciousness leader tortured to death by police, who is now founder of Agang, a new political party intended to break the ANC's hold on power.

"What is going on now would have made [Mandela]sad. His legacy is not being honoured, not just by the ANC but by society. When I look around, the gap between what he stood for and what is happening is huge. What we as a society need is to commit - as we celebrate his life and mourn his death - to returning to the values he held of servant leadership." The dissenting voices will find it hard to be heard this week. People like Vusimuzi Ngcobo, a tourist guide in Soweto, are not prepared to compromise on their view of Mandela. "He was a man of vision, one of the greatest men of his century," he says.

Official events begin on Tuesday, with a mass memorial service planned at the FNB Stadium on the edge of Soweto. A huge crowd is expected, well in excess of the stadium capacity of 95,000. But the people have beaten the government to it. At Mandela's home in the affluent Johannesburg suburb of Houghton, hundreds of people join together in singing liberation anthems and songs of praise to their departed hero. A little girl, accompanied by her father, holds a bunch of flowers torn from a garden, complete with weeds - an unintended metaphor for Mandela and the less principled men who followed. Precious Ncayiyana, a pharmacist, carries a painting of Mandela made from old newspaper clippings, all of them about him. She intends to drive the painting's creator to Pretoria so that he can record the body of the great man lying in state.

"It's my way of contributing to Madiba's legacy," she says. "He's gone, but his spirit lives on." Nelson Mandela was raised a Methodist and presumably not given to supporting canonisation. With death, though, his ascent to sainthood is assured. One suspects that a man like him, aware of his own faults, would have preferred people to be a little less rapturous and a little more critical. But South Africa needs its hero, and the world's leaders need their photo opportunity. Nelson Mandela is big business.