When Anthony Fauci speaks, his voice has a hint of a rasp, a lot of Brooklyn swagger and a reassuring glimmer of optimism. That combination has meant that throughout the coronavirus pandemic, as the renowned infectious-disease expert has offered information and advice to a jittery and beleaguered public, he has also communicated fatigue, toughness and the fundamental belief that science will hash out a path through the darkness and towards the light.

For that well-calibrated delivery and his deeply human manner, this nation has both lionised and demonised him. Give him a medal; throw him in prison. We are a nation of extremes. So this is what we do.

Fauci, who has been the face of the country's pandemic response, announced that he will retire in December. He will leave his position as chief medical adviser to President Joe Biden and he will step down from his job of the past 38 years as Director of the National Institute of Allergy and Infectious Diseases. He plans, he said, to teach and write, and mentor the next generation of scientists.

For the past three years, this trim, grey-haired doctor with the wire-rimmed glasses has been the vessel into which the country has poured all its fears and frustrations. He is hero and tormentor. Truth-teller and unreliable narrator. He has borne our angst. And through it all, he has shown the public nothing but patience and decency — and only the occasional flares of angry exasperation mostly reserved for a senator named Rand Paul, the Republican from Kentucky, whose preferred response to the pandemic might be summed up as “do as little as possible”.

Fauci’s admirers greeted his retirement announcement with a flurry of adulation for his lifetime of public service and his steady hand during historically turbulent times. Biden praised his sweeping impact not just on Americans but on people around the world. “As he leaves his position in the US Government, I know the American people and the entire world will continue to benefit from Dr Fauci’s expertise in whatever he does next. Whether you’ve met him personally or not, he has touched all Americans’ lives with his work.”

And former president Barack Obama expressed thanks not only for what Fauci has done but also eager anticipation for the impact that Fauci will have in the future. “I will always be grateful that we had a once-in-a-century public health leader to guide us through a once-in-a-century pandemic. Few people have touched more lives than Dr Fauci — and I’m glad he's not done yet.”

But if his political critics, particularly those Republicans in Congress, have their way, Fauci will spend a significant portion of his retirement testifying before one investigative panel after another. They blame Fauci for everything from the coronavirus itself to mascne. The disdain has brought threats. The doctor needs security.

And yet he has carried on. That has been the most remarkable thing of all. He could have retired long ago. He could have silenced the angry mob by going on his way. Fauci’s critics were so childish that they mocked his bad arm when he threw out baseball’s ceremonial opening pitch in 2020 and it missed the mark. President Donald Trump mocked Fauci. And still, the doctor patiently offered the country his most informed advice.

Throughout his career, Fauci, 81, has dealt with a host of virological menaces — Aids, Zika, Ebola, Covid-19 — but it may be that none have been quite so confounding as disinformation, as the disregard for facts, as the demonisation of intelligent inquiry. This is a scourge of our own deliberate making. As he said during a recent interview on MSNBC, the country is at a place “where we can see something in front of our very eyes and deny it’s happening”.

So many of our growing cultural bugaboos came to a head in our reckoning with Fauci. He is an intellectual at a time when many deem book-learning dangerous and cheap. He epitomises academic journals and peer-reviewed articles. Meanwhile, folks are burning books they don’t like or they don’t understand or that simply make them sad. As a scientist, Fauci deals in facts, when so many barter in free-floating feelings. He focuses on a singular truth, when so many others rhapsodise about speaking their personal truth. We want to kill the messenger, ignore his message and bury the horse he rode in on.

Fauci endured. During regular briefings to the public, he stood unmoved behind Trump while the former president leant into the microphones and cameras hoping to magically wish away the pandemic. Fauci with his head resting in his hands. Fauci rubbing his forehead. Fauci staring off into the middle distance. Fauci with his hands gripped into a fist. Fauci stepping to the lectern to publicly contradict Trump while Trump looked on.

Fauci is a man who is publicly at ease with contradictions at a time when people want absolutes. What politicians call flip-flopping and voters call mistakes, he calls science. In science, there’s a difference between a hypothesis and a theory. The former is an educated guess; the latter is an assessment based on data. It takes a while to get to the answers, to settle on a theory. But we know that. We learnt that in middle school science. Trial and error. The sludge test. Our forgetfulness has been wilful.

But Fauci just kept telling the public what he knew, where things stood, what he hypothesised at any given moment as he awaited the data. He was calm even as his voice got raspier and he looked ever more tired. It was terrifying knowing that we were living in a real horror movie and there was no guarantee that a hero would come along to save the day. So some people turned Fauci into the hero and started making posters bearing his name and dolls bearing his face. We “hearted” him and Brad Pitt portrayed him on Saturday Night Live. Yet amid all of that adoration was an overworked scientist who had been at his job since the start of the Aids crisis when he had watched every single one of his patients die and there wasn’t anything he could do, no matter how much those patients believed that just maybe some hypothesis would save them. Fauci kept going.

We placed all our burdens on Fauci. He has carried our anger and our hope. We rushed to embrace every sliver of optimism and then became enraged when it proved to be a mirage. We did not want to be inconvenienced, but we wanted to be saved. And when it looked like we were saved, we accused him of putting us in danger in the first place. Fauci was lionised and demonised. Because that is what we do. We continue to demand certainty in uncertain times.

• Robin Givhan is senior critic-at-large writing about politics, race and the arts. A 2006 Pulitzer Prize winner for criticism, Givhan has also worked at Newsweek/Daily Beast, Vogue magazine and the Detroit Free Press