Editor's Note: (John Avlon is a CNN senior political analyst. The opinions expressed in this commentary are his own. View more opinion articles on CNN.)
(CNN) Thirty years ago this weekend, the Berlin Wall fell -- and the world changed.
It felt like the future was endlessly bright.
The Cold War had been won without firing a shot and an "Evil Empire" was ending.
It was a celebration of liberation and the rise of liberal democracy as a new consensus, elevating individuals over ideological excesses.
Looking back, the gap between the hopes of 1989 and the facts of 2019 is stark.
We've gone from tearing down walls to building them -- from autocrats being on the run, to autocrats on the rise. With technological surveillance states secured by fear and greed, democracy itself seems in retreat.
The "liberal idea" itself was declared dead by a former KGB officer who has been president of Russia for most of the past 20 years, Vladimir Putin -- someone who called the end of the Soviet Union the 20th century's greatest tragedy, all the while trying to roll back freedom's gains in countries like Ukraine. Meanwhile one-time liberal student leaders like Hungary's Viktor Orban have become ethno-nationalists who champion illiberal democracy and seek to divide a united Europe.
We hear the old Soviet rhetoric of "enemy of the people" spoken by a US president who questions the value of NATO and refuses to criticize a Russian president who meddled in our election to his benefit.
All while America is becoming less free, according to Freedom House. The US now ranks after 51 other nations that are considered "free." Compare this to not even a decade ago when we ranked behind just 30.
We've seen a degree of historical amnesia kick in; a growing fascination with socialism among a generation born after the end of the Union of Soviet Socialist Republics. And, even worse, we've caught glimpses of a kitschy romanticization of Communism, which does deep disrespect to the 100 million people who were killed in its name. Our contemporary impulse to attack policy differences in our democracy is a slippery slope to a Soviet state.
These are arguments we hoped would be on the ash-heap of history by now. Then again, when I read about the fall of the Berlin Wall in high school, I never imagined that defending liberal democracy would be a core responsibility of my generation.
But there is a defiant optimism that lingers as a legacy from the spirit of 1989, because none of the experts predicted the fall of the Berlin Wall or the Soviet Union.
It came about not just because of Western leaders like Ronald Reagan, Margaret Thatcher and Pope John Paul II, but primarily because of countless small acts of courage by people behind the Iron Curtain who refused to live in fear -- small bands of dissidents who would not conform and give lip service to lies big and small.
They spoke out at personal risk and the power of their examples slowly gave courage to others, until many were marching in solidarity, from shipyards in Poland to public squares in Prague.
And that's where a playwright and prisoner turned Czech president Vaclav Havel said this during his country's "Velvet Revolution:"
"Truth and love must prevail over lies and hatred."
I've been thinking about that quote a lot lately. It resonates in our times.
The 30-years' drift from the hope that accompanied the fall of the Berlin Wall teaches us that we cannot take progress or peace for granted. There is no end of history. But freedom-- like truth and love and liberal democracy-- is worth the fighting for, in a spirit of solidarity.