Even experienced from 500 miles away in the local cosiness of the Glasgow Film Theatre, it’s as if an angel has burst through our ceiling and is addressing us with her holy message. Such is the visceral ferocity of the National Theatre’s production of Tony Kushner’s Pulitzer-winning play, Angels In America. It’s wincingly relevant, bar the lack of smartphones and the internet; simply swap the name of the incumbent president and play a short round of spot the difference. Set between 1985 and 1990 but written in 1993, the play’s subtitle is A Gay Fantasia On National Themes. The national themes of America seem to be a constant, circular conversation, but Kushner finds hope amidst the dread of wondering if you are living in the end times, the devastation of the AIDS crisis, and the bravery of those affected by the illness.

Beginning with everyone at absolute breaking point, every scene feels like a monologue that could end many other plays. The total running time is well over three hours, however the dynamism and energy of the hugely talented cast pushes you through, creating a dense emotional experience without veering into sentimentality or sensationalism. The sheer stamina of the cast is enough cause for awe but they match their unwavering strength with phenomenal performances, rooting the hopeful dreams and chaotic reality of each character in undeniable humanity. Denise Gough is plausibly, defiantly ill but saner than most as visionary dissatisfied Mormon wife Harper, whilst Glasgow’s own James McArdle manages to tread a very fine line in portraying the many facets of the selfish but conscientious and self-torturing Louis. Andrew Garfield’s AIDS-afflicted scion prophet Prior Walter is gloriously camp, in a way that previous productions – the HBO adaptation springs to mind – shied away from.

At curtain call, the stage managers and crew are behind the cast and receive their own thunderous applause. The term “set design” doesn’t do justice to the worlds upon worlds that shift and shake through the proscenium arch. Sluicing through centuries, continents and celestial bodies, the neon haze bordering separate segments of stage echoe Harper’s observation of the O-Zone layer and its protective qualities. Hospital rooms, park benches and apartments are like dioramas, each part a moving cog, malleable in this great parallel machine of experience. Atoms, planets, bubbles – each to their own and all together.

What is particularly eerie is the discussions around identity politics, conversations happening in the mid-80s and early-90s that are being repeated digitally across social media today; conversations that frequently fall apart. But the infernal synchronicity of the play’s plot is inconvenient ideologically but continually surprising and strangely affirming. To see such a compassionate representation of Reaganites, criticising their undeniable power and beliefs but also appreciating their inalienable frailty is something that society seems to be sorely lacking now more than ever.

Particularly moving is the depiction of Roy Cohn, the lawyer who fought to ensure the execution of the Rosenbergs while raging and refusing to consider his disease as AIDS instead of the liver cancer he claimed it to be, yet still as a dying man who has a right to care. His takedown of labels and identifiers, the structure of power and influence in America, is blistering. Trump and Murdoch met through him, making me realise that the world is living not through Reaganism before and Trumpism now but Cohnism. The play’s relevance today calls into stark consideration the very concept of progression and whether history is doomed to repeat itself. What good is theory when you’re trying to survive a plague?

2017 marks 50 years since certain aspects of homosexuality were decriminalised in England and Wales. Though there has been significant steps forward that are worth commemorating, Angels In America forces us to confront the great work necessary for establishing and maintaining rights that, in its persistent relevance, makes for an uncanny but essential theatrical event.