“Here we are, the most racist team in the country”. So goes the favourite ditty of fans of Beitar Jerusalem, the subject of the engaging BBC Storyville documentary Forever Pure.

Israel’s most popular team, Beitar is considered to be the club of the people. Although not always as successful on the pitch as their traditional rivals, their fanbase is the envy of every team in the country, and sufficiently influential to be courted by politicians as mighty as Prime Minister Benjamin Netanyahu.

However, the club is also controversial, having traditionally represented a right wing, nationalist and overwhelmingly pro-Jewish viewpoint.

Forever Pure tracks the club in the 2012/13 season, when football took a back seat and the only show in town was the decision to sign Dzhabrail Kadiyev and Zaur Sadayev on loan from Terek Grozny. Both players are Chechen and, more importantly (at least from the point of view of Beitar’s hardcore fans), both are Muslim.

What follows is a scarcely believable standoff between the club heirarchy, led by chairman Itzik Korenfine and controversial owner Arcadi Gaydamak, and the hardcore ultra group known as La Familia, who consider the decision to allow Muslims to pull on the famous shirt to be the ultimate betrayal.

Forever Pure portrays a club pulling itself apart, torn between the modernising vision of its leaders and the archaic beliefs of its fans. The documentary makers were given close access to the team throughout that troubled season, and the result is spectacularly intimate.

As the grand drama plays out in the stands and on the pitch, we focus on the tunnel, the changing rooms, the board rooms. At the centre of this club’s battle to define, escape or even understand its identity are some complex characters.

Gaydamak, the Ruso-Israeli businessman who makes no secret of his motives for purchasing Beitar: influence. Like Netanyahu before him, Gaydamak sees the loyalty of the club’s fans as a powerful tool for advancing his political ambitions. The decision to sign the two Chechen players, groundbreaking though it may be, has more to do with his wish to advance business interests in Grozny than any great desire to modernise the club.

Itzik Korenfine, the former Beitar legend and now club chairman, who risks his legacy and his family’s privacy to try to tackle racism. Korenfine bravely takes on La Familia, saying “There is a new reality, and everyone will need to adjust to it. If you keep behaving like this, I will do everything to keep you out of Teddy stadium”.

Ariel Harush in happier times.

Ariel Harush, hero turned pariah

Ariel Harush, the club’s young goalkeeper, captain and all round hero. In the opening scenes, we see him hoisted on the shoulders of adoring fans who chant his name. All that changes after Harush welcomes the two Muslim players to the club in a press conference, and it’s hard not to feel for him as he tries to come to terms with his new status as a pariah of the hardcore.

Most importantly, Kadiyev and Sadayev; two young men who find themselves catapulted into a situation they do not seem to fully comprehend. From their arrival, they are sworn at, insulted, and told repeatedly to go home. On their first day of training, a La Familia ultra shouts that the board have “brought us two Muslims, not football players”. At one point, Sadayev cannot understand why fans keep calling him an Arab.

What should have been the adventure of a lifetime, and a chance to progress their fledgling careers abroad, quickly turns into a nightmare for these likeable Chechens. The reaction of La Familia when Sadayev scores his first goal for the club is incomprehensible for any football fan, and indicative of a society which one Beitar fan describes as “injured”. That the two players respond with such patience and professionalism to the mayhem around them is testament to their character, and the feeling persists that they’re better men than Beitar deserve.

Perhaps the most illuminating voice is that of Argentinian player Dario Fernandez, who sees the whole situation with the same outsider’s eye as the viewer. Fernandez despairs at the lack of backing Kadiyev and Sadayev receive from their team mates, stating that only he and Harush have made any real effort to defend the Chechens to the fans. Instead of the welcome embrace of the dressing room, which should be their refuge from the horrors of the outside world, the newcomers find isolation as the Israelis in the team seek to avoid being tainted by association like Harush.

Forever Pure is a challenging, but wonderful, documentary. It offers a window into a club that has got it horribly wrong, where the societal and political sideshows that so often attach themselves to football (sometimes to positive effect) have been allowed to spiral out of control. The delicate portrayal of the central figures allows us to see what the club’s civil war is doing to decent (and not so decent) football people. You will struggle to find a documentary that shows so much about a club, a fanbase and a society. Watch it.

Storyville: Forever Pure was first shown on BBC Four on 4 December 2016. It is available to view on the BBC iPlayer until Tuesday 3 January 2017.