John Lennon’s Imagine has appeared at more Olympic games than most athletes. Having featured in the Summer Olympics in 1996 and 2012 and the Winter Olympics in 2006 and 2018, it was back once again at Tokyo’s opening ceremony, performed by a digital global supergroup and a children’s choir. “If the games were a song, Imagine would be the song,” said one organiser of a tune whose message (“Imagine there’s no countries”) would theoretically put paid to the whole event.

This was a considerable improvement on Imagine’s last prominent public outing. In March 2020, Wonder Woman star Gal Gadot decided to cheer up everybody on lockdown by asking 26 of her celebrity pals to film themselves singing a line, irrespective of their ability to hold a tune. The a cappella montage did at least provide the most terrifying phase of the pandemic with a shared moment of unintentional hilarity and a lasting monument to the hubris of well-meaning celebrities with nothing to do. One guilty participant, the actor Chris O’Dowd, put it down to “that first wave of creative diarrhoea that seemed to encase the entire world”. Of course, Gadot had to choose Imagine.

Imagine, which turns 50 in September, occupies a unique place in our culture. When the song’s producer, Phil Spector, first heard it, he thought it was “like the national anthem”; but like Spector’s reputation, that assessment has proved complicated to say the least. While some regard it as beautiful and profound, or at least unifyingly inoffensive, others damn it as a sanctimonious monstrosity. It was voted the UK’s favourite song lyric in 1999, the best single of all time in 2001, and the greatest song ever in 2004. Yet it has also been named as the worst song in the world so often that to despise it has become a cliché. “I am hardly the first writer to dislike Imagine,” wrote the critic Tom Ewing. “In fact, the laurels on the comment thread are likely to go to anyone who can make a really good case for its beauty, wisdom or excellence.” This cannot be put down to just its chronic overfamiliarity. Other played-to-death songs such as Hey Jude or Bohemian Rhapsody aren’t nearly as divisive. So what is it about Imagine that drives so many people crazy?

It is annoying that Imagine has been used to caricature a painfully complicated man as a gentle saint, so it’s essential to understand where Lennon’s head was at when he recorded the song in his home studio in Tittenhurst Park, Berkshire in May 1971. His experience of Arthur Janov’s primal scream therapy had enabled him to let go of the “father-figure trip”, he said. “Facing up to reality instead of always looking for some kind of heaven.” At the same time, Lennon and his wife Yoko Ono were in the throes of political radicalisation.

In 1968, he had written the Beatles’ Revolution, which told the counterculture to steady on there and drop the pictures of Mao. By the end of 1970, he was telling Rolling Stone: “I really thought that love will save us all. But now I’m wearing a Chairman Mao badge, that’s where it’s at.” Shortly after an interview with Tariq Ali and Robin Blackburn for the Trotskyist magazine Red Mole in January 1971, he wrote a new song based on their conversation. Combining socialism and feminism with a Black Panther slogan, Power to the People flipped the ambivalent opening line of Revolution into a call to arms: “Say you want a revolution/ We better get on right away.” The US New Left magazine Ramparts republished the interview under the headline “The Working Class Hero Turns Red”.

Lennon saw Imagine as a different kind of revolution. The black comedian and activist Dick Gregory had given him a book of positive prayer, which Lennon explained to Playboy in 1980 like so: “If you can imagine a world at peace, with no denominations of religion — not without religion but without this my-God-is-bigger-than-your-God thing — then it can be true.” Imagine, therefore, is protest rewritten as a secular prayer. The idea chimed with Ono’s “instruction paintings”, collected in her 1964 book Grapefruit, each of which began “Imagine…” Lennon later said that Imagine should have been credited to Lennon/Ono because “it was right out of Grapefruit” and her name was finally added in 2017.

The Yoko factor turns a lot of people off. While a song like Working Class Hero draws its political power from Lennon’s distinctive flinty sarcasm, Imagine is driven by Ono’s utopian whimsicality. It’s of a piece with the couple’s subsequent billboard campaign, “War is over! If you want it.” The idea that you can simply will a better world into being can seem like impotent New Age guff but the New Left’s philosopher-in-chief Herbert Marcuse was then arguing that imagining radical change was the essential first step towards realising it. The critic Robert Christgau acutely observed that Imagine was “both a hymn for the Movement and a love song for his wife, celebrating a Yokoism and a Marcusianism simultaneously”.

People who find Imagine about as deep as a Keep Calm and Carry On poster might be surprised by how seriously contemporary critics took it, but it is a startlingly radical lyric wrapped in a musical comfort blanket. Running from the myth of Beatle John, Lennon was desperate to shed every form of baggage, and Imagine magnifies this process of renunciation to global proportions. Like Gimme Some Truth, God or Give Peace a Chance, it is a list of things to reject. The first verse scraps heaven and hell; the second bins nations, religions and war; and the third abolishes possessions and poverty.

As the chorus acknowledges (“You may say I’m a dreamer”), that’s a lot for one song to ask for. Its haters are divided between those who consider this prospectus anodyne drivel and those who find its picture of a godless, classless, borderless world “a vision of hell”, as one writer put it. Lennon told the NME that it was “anti-religious, anti-nationalistic, anti-conventional, anti-capitalistic, virtually the Communist Manifesto, even though I’m not particularly a Communist and I do not belong to any movement”. He preferred “a nice British socialism” to “the way some daft Russian might do it”.

“Imagine no religion” angered the kind of people who had still not forgiven Lennon for saying the Beatles were more popular than Jesus but it was “Imagine no possessions” that became the main bone of contention. “Was it a millionaire who said imagine no possessions?” sang Elvis Costello in his 1991 single The Other Side of Summer. Lennon himself realised that he’d misjudged the next line, tweaking the inadvertently condescending “I wonder if you can” to “I wonder if we can” in at least one performance.

The visuals don’t help his case. Lennon decided to film the making of the album and a clip from the movie — John playing his white baby grand piano in his big white mansion — became the music video for Imagine. He should have anticipated that this tableau of smug luxury would sit uneasily with the third verse, but to be fair to him, he was at the time very happy to play benefit concerts and give money to all kinds of causes, including two of the Chicago Seven defendants, Biafran refugees and Clydeside shipbuilders, one of whom misheard the name of the donor and shouted out, “But Lenin’s dead!”

I’m not convinced that it’s inherently hypocritical for a rich man to imagine a different world, given that anyone who has a big enough platform to spread such a message is almost inevitably wealthy. Still, one has to love the card that Elton John sent to the couple at their extravagant home in Manhattan’s Dakota Building: “Imagine six apartments/ It isn’t hard to do/ One is full of fur coats/ Another’s full of shoes.”

By the time they moved into the Dakota in 1973, Lennon’s revolutionary phase had flamed out. Lennon biographer John Wiener argues that Imagine “seemed to many movement people a hymn to the New Left in defeat”. Not long after the hot mess of Lennon’s 1972 protest album Some Time in New York City, Richard Nixon won reelection in a landslide and Lennon made a brisk, bitter retreat from politics. The FBI, which had been monitoring him as a potentially dangerous radical, closed its file.

It seems remarkable now that when it was released as a single in the US, Imagine hung around the charts for no longer than Power to the People had done and was outperformed by Paul McCartney’s amiable Uncle Albert/Admiral Halsey. It didn’t come out in the UK until 1975, when it peaked at number six. McCartney angered his estranged friend by telling Melody Maker that he liked Imagine because it wasn’t as political as John’s recent stuff. Lennon shot back with a furious letter: “So you think Imagine ain’t political? It’s Working Class Hero with sugar on it for conservatives like yourself!! You obviously didn’t dig the words. Imagine!”

It’s the sugar that makes the song so portable. It may have the most comprehensive agenda of any hit single ever made but Imagine sounds modest, tentative and unassuming. On a compositional level, it is almost childishly simple. (You can hear an instrumental scrap of it, called John’s Piano Piece, in outtakes from the Beatles’ 1969 Let It Be sessions.) The basic track was recorded in less than half an hour (they used the second of three takes) and the subsequent string arrangement was extraordinarily restrained for a Spector production. The Tokyo version, orchestrated by Hans Zimmer, is far too grandiose; a thought experiment should not be oversold.

Imagine, therefore, lends itself to occasions when something hopeful but not overbearing is required. After Lennon was murdered in 1980, the song topped the UK charts for four weeks but its suitability for mourning is much broader than that. Stevie Wonder performed it in 1996 in honour of the victims of a terrorist bombing during the games, Neil Young reached for it at a 9/11 tribute concert and Madonna chose it to remember those who died in the 2004 tsunami. As Slate’s Katy Waldman wrote when it again became a song of grieving after the assault on the Bataclan in Paris in 2015, “No one who has just watched footage of families mourning their loved ones in the wake of a terrorist attack is ready to swallow a dose of unalloyed affirmation. The song seems veined with the sad understanding that its own dream is too simple.”

Yet at the same time, Imagine still carries enough of a residual political charge to have been banned by the BBC during the first Gulf War and (briefly) by the US radio network Clear Channel after 9/11. At the end of 2001, Rolling Stone called it “a new national hymn, a strong, quiet counterweight to the institutional psalms and fight songs… that have filled the air since the terrorist attacks.” Former President Jimmy Carter told NPR that on his travels around the world, he heard it “used almost equally with national anthems”.

Imagine is rather like a tourist attraction in your hometown: you’re so used to seeing it in the background that you forget why it’s remarkable. To be honest, I need never hear it again but I’ve warmed to it in recent years precisely because its naked idealism is so very uncool and so easy to deride. There has never been a song like it and it would take a supernatural blend of talent, ego and idealism for anyone to even attempt one. Can you imagine what Twitter would do if, say, Chris Martin tried it?

Unless I am seriously underestimating the global appetite for utopian socialism, most listeners are not embracing it on a literal level as a time-capsule of Lennon and Ono’s post-Sixties art-school radicalism. As Rage Against the Machine’s Tom Morello has said, “If people really believed the sentiments John Lennon expressed in that song, we would have had revolution in this country a long time ago.” It has become instead a generous vessel for all kinds of aspirations, both big and small. Three years ago, the Observer asked Ono what the word “imagine” meant to her and she replied simply: “To think of something to hope for.” You may say I’m a sucker but I find that idea hard to hate.