One of the first legislative acts of the Irish Free State in 1922 was to appoint a film censor empowered to cut or ban any film deemed to be "subversive of public morality". Over the years it turned out that virtually all films fell into this prohibited category, an absurdity that finally led to a withering away of the idiotic system of cultural repression that was making Ireland a source of universal ridicule. The censors were, however, right about one thing: cinema is inherently subversive. By its very nature it undermines certainties and preconceptions, opening eyes to how life actually is in all its disturbing diversity and challenging ambiguities.

Of course, given the commercial structure of the film industry, the medium frequently fails to live up to this radical potential. If unmentionable subjects are confronted at all in multiplexes it tends to be through humour and ridicule: laughter, as Michael Moore keeps insisting, is the natural voice of protest and dissent.

During the 1990s, television became a veritable nursery of satire that gradually infiltrated mainstream cinema via Steve Coogan, Ricky Gervais, Sacha Baron Cohen, and Armando Iannucci and has now produced Four Lions – a daringly outrageous film debut by Chris Morris, the pivotal figure behind the ground-breaking BBC radio show On The Hour and spoof current-affairs TV programmes The Day Today and Brass Eye.

His target is home-grown British jihadist terrorism. The plot focuses on a cell of four bungling Muslim wannabe martyrs plotting to blow up the London marathon from a terraced house in Doncaster. They're as gormless as a group of football fans, all the time messing about and taking the piss, a sort of Dad's Army who can speak Urdu. Two of them are invited to an al-Qaeda training camp in Pakistan – much to the envy of a Caucasian convert to Islam who likes to dress like an imam – but are kicked out for trying to take pictures on their mobiles of an American drone plane which promptly strafes the camp. Another keeps going to the same hardware shop to buy large amounts of bomb-making liquids.

"I use different voices every time," he explains.

"Show us."

"Here's my woman's voice."

"But you've a beard."

When his equally idiotic attempt to train crows to carry bombs goes explosively awry, a tone-deaf rapper joins up in his place. The ringleader Omar (Riz Ahmed), married to a NHS nurse with a young son thrilled at the idea of Dad becoming a suicide bomber, is forever mocking his far more religious and pacifist brother, who wants him to implement Sharia law in his family life. The group's sheer incompetence enables them to mingle unnoticed with the marathon runners dressed up in comic animal costumes that hide their explosives. Farce becomes tragedy as the equally incompetent police fire on all the wrong targets.

Can terrorism be funny? Morris is sending up neither Islam nor the victims of jihad atrocities: he's exposing the vicious imbecile nature of fanaticism through lampoon rather than politically self-righteous sound-bites. By humanising terrorism – as Downfall did with Hitler – Morris deglamourises its threat and neutralises the hysteria of fear that has been built up around it and has become its only strength. Now that's what I call a movie.

Some years ago, the exiled Russian poet Joseph Brodsky gave a reading of his work at the Gate Theatre. He spoke in Russian and after each poem Seamus Heaney read an English translation. It's doubtful if anyone in the audience knew any Russian but once or twice when Brodsky stumbled over a phrase he clenched his hand in frustration. The exactness of each of the words obviously mattered immensely to him, partly because he was banned from uttering them in Russia: he was expelled in 1972 after serving 18 months' forced labour as "social parasite" and would die in America in 1996 without ever returning home or seeing his parents again.

Andrey Khrzhanovsky's A Room And A Half imagines Brodsky returning to St Petersburg on a ferry from Finland, a journey that triggers memories of his childhood, the only child of a navy photographer who was denied promotion because he was Jewish and of a mother who worked during the war as an interpreter at an internment camp for German prisoners. The memories, culled from Brodsky's writings, flow "in no particular chronological order, like in a film" and are expressed with a voiceover narration through old photographs and archival footage combined with re-enacted moments and surreal animation evocative of Chagall and Magritte.

It's a magical film, perhaps over-long, but not without wry humour ("I'm sorry, Joseph, we never understood your poetry," his mother says – "I know," he replies) and joyous in its celebration of human spirit and the power of poetry.

A one-armed bell-hop at a run-down ski lodge becomes a running gag in Hot Tub Time Machine, a gross-out buddy comedy that aims to emulate last summer's surprise comedy hit The Hangover. Not surprisingly, it doesn't: humour can't be so readily programmed.

The gimmick is that a drunken John Cusack and a couple of pals from his misspent youth plunge into a ski lodge sauna in 2010 and emerge to find themselves back in the same lodge in 1986, "and I f***ing hate this decade."

Their terror is that if they fail to do exactly what they did back then they'll be trapped in the past and mess up their futures. The bell-hop still has his other arm and part of the fun is finding out how he lost it: a lame joke, if ever there was one.

What we get is Back To The Future with excruciating penis pranks in place of originality.

"I can't tell what's real anymore," wails Rooney Marta in A Nightmare on Elm Street as if unaware that she's in a remake of Wes Craven's 1984 slasher classic about a horrifically disfigured, knife-fingered maniac Freddy Krueger, who drives people to death by invading their dreams. Since the film is marketed on audience familiarity with Freddy, her bewilderment is tiresome. Music video director Samuel Bayer lights the night scenes like an Edward Hopper painting but otherwise fails to come up with anything fresh to sustain interest.

Roger Kumble's Furry Vengeance marries George of the Jungle's Brendan Fraser to Hannah Montana's Brooke Shields and plonks them with High School Musical 3's Matt Prokop as their disgruntled teenage son in a virginal Oregon forest where Fraser is construction manager in charge of bulldozing the trees to make way for an 'eco-friendly' housing development.

The animals, led by a cunning raccoon rebel and communicating in cartoon-like balloons with images instead of words, subject Fraser to a wildlife variation of Home Alone-style punitive humiliation.

Adults might find it over-played and perhaps too obvious, but watching it unfold in a cinema packed with schoolchildren there was no doubting its appeal, particularly the ruder moments.

Winner of the Berlin Golden Bear and nominated for a best foreign language Oscar, Claudia Llosa's The Milk of Sorrow puts us inside the mind of a stoical and chronically shy Peruvian girl who feels so tainted by the rape of her mother by insurgents – one must presume members of Shining Path – that she puts a potato inside herself to escape a similar fate.

Through her daily struggle for survival we glimpse the contrasting lives of the village, where her family make a living organising traditional weddings, and the city, where she works as a maid for a snobbish pianist who, over-hearing her secret songs ("We must sing to hide our fear"), turns them into a showpiece at a recital.

Shot against a colourful landscape that counter-points the sombreness of the story, this is a beautifully nuanced example of allusive Latin-American storytelling.

Paul Lynch is away