Whereas its history is rich in valour through decades of oppression and turbulence, Mandela, now living quietly and permanently in his rural boyhood home in the Transkei, may secretly be glad to be too infirm to attend the birthday bash in Bloemfontein. It was in this city, capital of the former Orange Free State, that a handful of idealistic black people gathered in a small Wesleyan church on January 8, 1912, to demand for the "native" majority rights denied them by their country's white rulers: by the end of the gathering the ANC had been born.
But today, 100 years on, the question increasingly confronting the former liberation movement-turned-government, from within and beyond its own ranks, is an unhappy one: how did the corrupt, incompetent government in office today emerge from the high ideals its epic heroes like Mandela fought so hard to achieve?
South Africa under Jacob Zuma, the uninspiring state president and ANC leader, is plagued by the ruling elite's rampant corruption, catastrophic levels of unemployment among the young, income distribution as skewed as anywhere on earth and plummeting education and healthcare provision.
"Instead, we are left with a massive post-liberation hangover due to the arrogance of power and seemingly unstoppable greed and graft," writes South African author Heidi Holland in her biography, 100 Years of Struggle: Mandela's ANC, published this weekend. "South Africa's liberation euphoria has faded to the point where almost everybody acknowledges that we are not living in the country for which Nelson Mandela and many others suffered years of police harassment and devastating imprisonment."
Mandela's fellow Nobel Peace Prize winner, Archbishop Desmond Tutu, a hero of the anti-apartheid struggle, has voiced his disgust at the cronyism, patronage and degenerating ineptitude of Zuma and his ministers by saying: "They stopped the gravy train just long enough to get on themselves." He went on to say that Zuma's administration is "worse than the apartheid government" and that he would "pray for the downfall of the ANC".
It is all a far cry from nearly half a century ago when, on April 20, 1964, Mandela stood in the dock in the Supreme Court in Pretoria charged with sabotage and planning guerrilla warfare against the apartheid state. His words, in an epic four-hour closing statement, reverberated around the world, providing a manifesto of belief and moral values for anti-apartheid campaigners everywhere.
He explained to Justice Quartus de Wet his political ideals and admitted he was the leader of Umkhonto we Sizwe (Spear of the Nation), the infant guerrilla wing of the then outlawed ANC. Mandela said in the half-century before Umkhonto was born the ANC had been committed to non-violence in the struggle for black freedom. But said: "The hard facts were that 50 years of non-violence had brought the African people nothing but more repressive legislation, and fewer and fewer rights."
The final sentences he uttered in his statement from the dock, words which were banned from publication under apartheid law but which nevertheless became renowned, were: "During my lifetime I have dedicated myself to this struggle of the African people. I have fought against white domination, and I have fought against black domination. I have cherished the ideal of a democratic and free society in which all persons live together in harmony and with equal opportunities. It is an ideal which I hope to live for and achieve. But if needs be, it is an ideal for which I am prepared to die."
Justice de Wet adjourned for three weeks to consider his verdict. On return, he pronounced Mandela guilty but said he would not hang but go to prison for life.
It is not hard to imagine that Mandela is reflecting on that time today as he gazes from his armchair, blanket across his knees, through the picture window of his modest house across Transkei's rolling green hills. What he thinks of the current generation of his successors we may never know. The ideals he was prepared to die for are such a long way from the beliefs of modern ANC leaders such as former spokesman Smuts Ngonyama, who said of one of his dodgy business deals: "I didn't join the struggle to be poor." It was a remark that epitomised the prevailing culture of entitlement under Zuma compared with the self-sacrifice that epitomised the greatest politicians of the Mandela era.
Zuma has just spent some R400 million (£32 million) on expanding his lavish private home in Zululand where his five wives and innumerable children live. The expansion includes three sets of air-conditioned underground living quarters reached by lifts, a clinic for the family, a gymnasium, 20 houses for security guards, underground parking and playgrounds. Entry is through a 250-yard-long tunnel from a helipad. Zuma has spent a similar sum on upgrades, including saunas and swimming pools, of his official residences in Cape Town and Pretoria.
In countless high-profile cases top ANC leaders such as Cyril Ramaphosa and Tokyo Sexwale have moved from high-idealism politics to the private sector, becoming Russian-style billionaires, without blinking an eye. Enrichment displaced racial justice as their key concern, as skewed black economic empowerment laws served mainly the ANC elite. Ramaphosa, once the leader of mineworkers in the fight against apartheid, now runs the 145 McDonald's restaurants in South Africa in a 20-year deal with the fast food chain.
Allister Sparks, former editor of the liberal Rand Daily Mail, banned by the former apartheid regime, and a lifelong campaigner for black emancipation and confidant of Mandela, laments: "The Zuma administration is a failure. The country is sinking into a morass of corruption, service delivery failure, wasteful expenditure, incompetence and general maladministration. It is divided, directionless and devoid of ideas. It is paralysed by infighting, with factions clawing at each other for personal gain. That is the road to a failed state. Can the electorate call a halt? We are approaching a sticky stage now, as the Zuma administration slides into decline and the wrath of the people begins to stir."
The wrath of people such as Xoliswa Jayiya, 23, a university graduate who lives in Soweto, the sprawling black township. "The ANC is not what it used to be," she said. "They are corrupt to the core, which is unacceptable. Quality and standards are horrible. They did a great service but that is in the past and we cannot live in the past.
"In their disillusion, voters might turn to the political opposition over these guys who fly to Dubai or Switzerland to see their girlfriend," a reference to a Zuma minister, Sicelo Shiceka, who flew first class and stayed in five-star hotels to visit his girlfriend in a Swiss prison on drug-dealing charges.
Today's programme, beginning at the Wesleyan church where the ANC began, illustrates the movement's internal crisis. Zuma, who has vowed "we will rule until Jesus comes back", is the only person who will make a speech: that is against the party traditions that all the top leaders address the party faithful at the annual birthday meeting. The decision has been made – ahead of a new ANC leadership election this year – in order to gag the rabble-rousing ANC Youth League president, Julius Malema, who is a sworn enemy of Zuma. Malema, who seeks nationalisation of the country's mines, is awaiting the outcome of his appeal against a five-year suspension from the ANC for being disrespectful to the party's leaders and flouting the constitution. He has been compared to a wounded snake who, if given the chance, could bite Zuma and bring the entire house of cards down.
Malema has all the attributes of a demagogue, but with more than nine million black people earning less than the equivalent of one pound a day, making black poverty the burgeoning key political issue, he has fertile soil in which to sow his brand of incendiary politics.
Since coming to power in 2007, Zuma has shown scant regard for South Africa's institutions of democracy enshrined in one of the world's most progressive constitutions, hammered out in the negotiations that preceded Mandela's election as South Africa's first black state president in 1994. Zuma is working to subvert the constitution and the limits it imposes upon him. He seeks a pliant judiciary and lost no time in abolishing the country's independent and top anti-corruption agency, the Scorpions, which tried unsuccessfully to indict him for accepting bribes in a multi-billion rand arms deal with Britain's BAE Systems and other European arms manufacturers.
Sometimes, under Zuma, South Africa feels to some extent like entering a time-warp back to the 1980s when the apartheid state's rulers were at their most paranoid. Recently, South Africans woke up to find whole pages of their newspapers blacked out in the face of punitive action from the office of the president as draconian secrecy legislation passed through parliament that could send journalists to jail for 25 years for exposing presidential and ministerial corruption. If all this was happening in the 1980s, events in South Africa would be the focus of sustained international attention. Back then the country's apartheid sins were the supreme litmus test of where people stood on a range of human rights and international issues.
The opposition in parliament wore black as the legislation was introduced by Zuma ally and state security minister Siyabonga Cwele, whose wife Sheryl was recently convicted of smuggling into South Africa hundreds of thousands of pounds worth of cocaine in collaboration with Nigerian criminals. As journalists in parliament filed out after the vote, ANC MPs mock-applauded and shouted: "Bye bye."
The theme of unity will be at the heart of today's celebrations, but will prove difficult to maintain in a deeply divided and troubled movement. Political analyst Joe Mavuso says the display of unity will be short-lived as the faithful depart Bloemfontein to contemplate an unclear and hazardous future.