Every September, Indonesia seems to open an old book once more, its pages filled with tears, suspicion and questions that have never been fully answered. The 1965 events known as Gestapu are not merely an entry in a school textbook. They are a collective wound whose traces still appear in family memories, in political conversations that suddenly harden, and in the way the nation looks upon its own past.
There are many ways to approach these events. We may ask who masterminded them, who bears the greatest guilt, and who has the strongest claim to be called a victim. Such questions matter, and historians continue to test them with evidence and scholarly honesty. This essay, however, takes a different path. It does not set out to put the past on trial, but to hold up a mirror to the present. The question it asks is simpler: what can a nation learn from a tragedy in which some of its own people set about destroying one another?
A Tragedy That Changed the Nation's Face
At the end of September 1965, some senior army officers were killed. The event became the trigger for a chain of consequences far larger than itself: a shift in power, the banning of a political party, and waves of violence across many regions that claimed an enormous number of lives. Estimates vary widely, from hundreds of thousands to more than a million.
Numbers are easy to read and easy to forget. What is harder to picture are the faces behind them: the neighbour who exchanged a greeting one morning and became, the next day, someone to be suspected, shunned or made to disappear. Within a matter of months, fellow citizens who had lived side by side turned to mutual suspicion and hostility. The tragedy revealed how thin the line is between civilisation and chaos when fear is nurtured for longer than reason.
When Ideology Becomes a New Religion
It was an age in which ideology was not merely a set of ideas but an identity, a loyalty, even a creed. Nationalism, religion and communism each demanded the full allegiance of their followers, and the space for standing in the middle grew ever narrower.
The lesson here needs careful wording, because not every ideology stands equal before the constitution. Indonesia is founded on Pancasila and the 1945 Constitution, and the state has settled its position. Through MPRS Decree No. XXV/MPRS/1966, the Indonesian Communist Party (PKI) was dissolved and declared a banned organisation, and every activity spreading or developing the doctrine of communism/Marxism-Leninism was prohibited throughout Indonesia. That decree remains in force today.
Why is that doctrine regarded as so dangerous? The decree rests on two considerations. First, communism/Marxism-Leninism is judged to be incompatible with Pancasila, since a creed rooted in materialism and class struggle is hard to reconcile with Belief in the One and Only God, with unity, and with deliberation as the way to resolve differences. Second, its adherents, the PKI above all, had on several occasions in the Republic's history attempted to overthrow the lawful government by force. History records a series of events that the state links to this, from the Madiun rebellion of 1948 to the events of 30 September 1965. A doctrine that places the goals of struggle above human life and dignity ends, in the end, by demanding victims.
Yet there is something else worth guarding: the way a nation defends itself. When an idea, however sincerely held, is treated as an absolute truth that may not be questioned, people begin to lose the ability to see one another as human beings. The political opponent becomes an enemy, and a difference of opinion is regarded as a sin to be punished. The second lesson of 1965 is that vigilance against ideological threats must be accompanied by self-awareness, so that vigilance itself does not degenerate into blind hatred.
The Danger of Inherited Forgetting
Most of those alive today did not live through 1965. But what has reached them is not vengeance; it is emptiness. Many young Indonesians today know almost nothing about the PKI: what it fought for, why it was banned, or what happened at the end of September 1965. For some, Gestapu is merely a word that surfaces on their timelines each year and then sinks again. Its history has slowly worn away from classrooms, from television and film, and from everyday conversation, and in some places it seems to have been deliberately erased.
Such emptiness is no less dangerous than vengeance. A nation that does not know why a tragedy happened will be unable to recognise its warning signs when it returns in a new guise. That emptiness is also easily filled: by clipped videos, by half-true stories, by interpretations bent to serve a passing interest. A generation that is not given a complete history will take one from whoever tells the story first and loudest.
In this respect, the greatest danger is not the coal passed from hand to hand, but the fire forgotten until no one remembers how it once burned or what it consumed. Our task, therefore, is not to cool a vengeance that was in truth seldom inherited, but to fill the emptiness with knowledge: a history that is honest, complete, and told with a cool head to those who have never heard it.
Remembering Clearly and Vigilantly
To forget history is dangerous, and we are watching the proof in a generation growing up without knowing it. But remembering, too, must be done properly. To remember does not mean reopening old hostilities, nor does it mean softening our stance towards what the state and the constitution have decided.
To remember is to say plainly what happened: that army officers were killed, that the violence which followed claimed a great many lives and is acknowledged by the state as a gross human rights violation, and that the state subsequently banned the PKI and prohibited Marxism-Leninism. That prohibition is no accident of history. It forms part of this nation's answer to those events, and it remains part of our legal order.
But mature vigilance is different from hatred. We can safeguard the foundations of the state without cultivating hostility towards fellow citizens. We can honour the victims without turning grief into new hatred. A healthy history does not urge us to look for enemies; it helps us recognise mistakes and dangers so that they are not repeated.
This stance demands several things. First, the honesty to tell the story whole, without reducing it to slogans. Second, the humility to admit that research and testimony continue to grow. Third, an education that gives young people understanding rather than mere rote learning or prohibition. And fourth, loyalty to Pancasila and the constitution as our shared anchor, so that our vigilance does not become a pretext for fresh violence.
Guarding Against a New Face
A banned ideology does not always return under its old name, symbols and banners. That is why the phrase 'new-style PKI' has emerged, used to voice concern about attempts to revive the doctrine in subtler packaging: ideas that never call themselves communist yet carry the same content, efforts to whitewash or twist history, or calls to abolish Pancasila as the foundation of the state.
This concern finds fertile ground in the emptiness described above. A generation that does not know its history is easily drawn to attractive packaging, such as social equality framed within social justice, the defence of the oppressed but fostering hatred towards other groups (in accordance with Marxist teachings), or criticism of inequality, without realising from what roots and tradition those ideas come, or where they once led this nation. The demand for social justice is itself legitimate and fully consistent with the fifth principle of Pancasila. What deserves vigilance is when it is made a doorway for a doctrine that contradicts the foundation of the state.
The law, too, has already set up its fences. Law No. 1 of 2023 on the Criminal Code, in force since 2 January 2026, provides in Article 188 that anyone who publicly spreads and develops the doctrine of communism/Marxism-Leninism, or any other ideology contrary to Pancasila, may be punished, with heavier penalties where the aim is to change the foundation of the state or where unrest results. Article 189 covers founding organisations that adhere to such doctrine, and Article 190 covers public statements intended to abolish or replace Pancasila. These provisions trace back to Articles 107a to 107f of the former Criminal Code, added by Law No. 27 of 1999. At the same time, Article 188(6) makes clear that study undertaken for the purposes of scholarship is not punishable, so that examining this history and doctrine academically remains open.
Yet the history of 1965 also teaches another side of vigilance. The label 'PKI', attached without evidence, once cost many people their lives, including those who were merely accused or associated. Guarding against a new face must therefore never mean pointing a finger at anyone who thinks differently. Healthy vigilance works through knowledge, evidence and fair legal process, as MPR Decree No. I/MPR/2003 itself requires when it says the prohibition must be applied justly and with respect for the law, democracy and human rights. It does not work through slander, persecution or vigilantism. Vigilance that violates human rights will only repeat the very mistake it set out to prevent.
Why It Still Matters for Indonesia Today
History never repeats itself in exactly the same form. Yet its patterns often feel familiar. Though the shape is different, the seeds of division that grew in 1965 can still be found in the age of social media. Slander travels faster, anger is more easily sustained, and people are increasingly judged by the group they belong to rather than by the content of their thoughts.
Political polarisation, propaganda, hoaxes and group fanaticism are the latest versions of an old mechanism: reducing the world to 'us' and 'them', then instilling the fear that 'they' are a threat to 'us'. The difference is that the machinery of dissemination now works in seconds and reaches millions at once.
For this reason, the lessons of Gestapu have not lost their relevance. They teach us to verify before believing, to ask before accusing, and to listen before judging. They remind us that a healthy democracy is not only about elections but also about the ability to disagree without denying one another's humanity. And they teach us that nurturing unity is not a task completed once and for all, but daily work that begins with small things: with how we speak, how we share news, and how we treat those who differ from us.
Epilogue
September will always return. With it comes the memory of one of the darkest periods in Indonesia's history: officers killed, followed by violence that took far more lives, and which the state has acknowledged as a gross violation of human rights. But the purpose of remembering is not to dwell in that darkness. We look back so that we do not walk towards the same abyss.
Perhaps that is the deepest meaning of commemorating Gestapu: that humanity must not be defeated by any ideology, and that Pancasila, the foundation of the state, must be guarded not with hatred but with knowledge, law and vigilance. A doctrine that once brought this nation to the edge of the abyss must not be allowed to return unrecognised, even when it arrives wearing a new face. Yet that vigilance must remain humane, for a nation that forgets its history will repeat it, and a nation that turns vigilance into an excuse for hatred will create new victims.
So long as knowledge guards our memory, law guards our boundaries, and humanity guards our hearts, September may keep coming without having to bring the same grief.
A great nation does not forget its tragedies, but one that can turn tragedy into a moral lesson for the future.
