The East German communist slogan that never needed updating was "Marxism- Leninism will triumph because it is true". All the other slogans that were regularly issued by the party to each town and village depended on the truth of that one. If you believed it, victory was a scientific certainty. Science had toppled God. Science was God, so Marxism had to be good.
It was probably sometime during the Thirties, during Stalin's purges, that Soviet leaders and most Russian intellectuals stopped believing their own slogans. Communism was doomed but the Great Patriotic War against fascism gave Stalinism a new lease of life. If the party slogans were window dressing, patriotism was for real. Then Gagarin beat America into space - and that was food for another generation. It was, paradoxically, only when a new kind of leader, Mikhail Gorbachev, decided the Soviet Union's only chance lay in becoming a Marxist social democracy that the propaganda failed.
But if the slogans were for years losing their potency at home they continued to work abroad: they frightened the pants off a whole generation of Americans and their ideological friends who really did seem to believe the Soviet myth that Communism was virtually invincible. Virtually. Its victory just might be staved off by the nuclear superiority of the West. If Communism did win - and they clearly feared it might - then it was there to stay for ever. Which was why alliances with right-wing tyrannies were necessary in the cause of anti-Communism.
But in the end Soviet-style Leninism was bound to fail because it was not the truth, as its potentates had long known. Stalinist dictatorship was like any other tyranny (which is where the devotees of anti-Communism were so wrong). It carried within itself the seeds of its own destruction.
When power at the centre implodes, the satellites fall like dominoes. But each society, when it can, prefers to make its own revolution, in its own way. Except for Romania, they all did it without bloodshed and, it transpired, despite the fears of the US ideologues, none of these nations had lost their soul.
Of these revolutions, the one I was best able to observe - for much of the time from within - was the peaceful East German revolution. After a fashion - as I found when I was East Europe secretary of the British Council of Churches through most of the Cold War years and visited East Germany some 76 times according to the visas in my passport - the GDR worked a little better than the rest of the Soviet empire. But by the Eighties unrest had set in.
The really angry were a young generation who had never known anything other than the GDR. The churches in the land of Martin Luther, the only public bodies not under state control, provided the outlets for their dissatisfaction. By the early Eighties, many clergy, sharing the general public frustration, started regular peace services.
"Peace" in GDR-speak was the ideological word that stood for all the party's ideals. So the church got in on the act and showed that Communism had no monopoly on peace. In church-speak "peace" also embraced justice and human rights. And so, protected by the church, an ever-growing dissident scene - at first just a few hundred - dreaming of a radically different GDR, came into existence. There were arrests and imprisonments but the scene continued to grow. Those who came to pray and protest feared German police batons but they knew the Red Army would stay in their barracks.
By early October 1989 the hundreds had turned to hundreds of thousands. There were fears there might be a German Tiananmen Square. But then, as even more Germans began fleeing - through Hungary to Austria - the Politburo threw in the towel. Ten years ago this Tuesday, the Berlin Wall fell.
The GDR leadership opened the Wall on 9 November. Their choice of date was almost a piece of German Romantic poetry. On that day in 1918 the Kaiser fell and a socialist republic was declared from the palace balcony and two days later the First World War ended with Germany's surrender. It was on that same date in 1923 that an angry, defeated war veteran - Adolf Hitler - tried, with his followers, to seize power in Munich. The police shot 14 of them dead. The Nazi party had its first martyrs, its flag draped in their blood. Then on 9 November 1938, to affirm the purity of the German race, the persecution of the Jews began in earnest. It was Kristallnacht: the synagogues blazed and the scene began to be set for the "final solution", for the gas chambers. And so, to round off the history of Germany's 20th century, the Wall that had become the symbol of a generation of fear was now no more than the stuff of thousands of concrete souvenirs. The date on which an old order had died, on which an ideology was born and then flamed, became the date on which it also perished.
Ironically, I watched the end of Communist rule in East Germany on television in Archbishop Tutu's study in Cape Town. We watched Stalinism die as apartheid was dying around us. I shared some of the delirious joy, but even then with foreboding. Revolutions, even peaceful ones, bring their own grave problems. Good things - and Russian people now miss them - went with the bad, as in every revolution.
The old order died not with a bang but with a headlong descent into the worst kind of uncontrolled and amoral capitalism, producing the current state of disillusion; not a guillotine, but just the old nomenklatura turning into the new mafia, with justice and human rights a pipe-dream now as then. It is no longer safe to go out at night in Moscow or in Johannesburg. The mafia rules. The future is a perilous thing.
Today the euphoria of 1989 has vanished. The Gemans, East and West, are not yet at ease with one another, but they are learning slowly and painfully to become one in spirit. How wrong Margaret Thatcher was to fear a united Germany. For it is good news for its neighbours. It has decisively shed its nationalist past. It is the least militarist and one of the most socially just of European nations.
Lady Thatcher, who has not been invited to Berlin to share this week's celebrations alongside Gorbachev and Bush, could not have been more wrong. Yet her fears tell us something - as does the behaviour of those youngsters still fed on a diet of war films who shout "Heil Hitler" at German tourists.
But they tell us something not about Germany but about ourselves. Perhaps it is not surprising that many Britons, with no revolution of their own for several centuries, find it hard to understand that a nation can really break with its dark past.
Canon Paul Oestreicher will be broadcasting `Thought for the Day' live from Berlin on Radio 4 on Tuesday.Reuse content