It's lunchtime in overcast Dublin, which sounds like the perfect time to have a drink, but in the basement bar of a boutique hotel Dylan Moran is nursing a herbal tea. He looks good, which is to say he looks like a slightly more rumpled John Cusack. It's been 10 years since the end of Black Books, the cult sitcom he co-created with Graham Linehan, which cemented a very particular image of Moran in the popular imagination – a misanthropic yet scruffily charming drinker. In person, Moran manages to appear both expansive and a little guarded. Instead of appearing on panel shows, he's spent the decade sharpening his deceptively rambling stand-up in unusual places (Kiev, Moscow, Kazakhstan) and popping up in movies. His attitude to TV is almost punk rock. "A lot of what appears on TV now is cheap content, it's filler," he says. "I don't want to do that shit." But when you've been on TV for a few years, and then suddenly you're not, the public starts to think that perhaps you're no longer… "Alive?" he offers.

In fact, he spent much of last year in the US. Moran did two tours, performed on David Letterman and wrote a TV pilot for ABC, although it's currently in turnaround. "That means they're not going to do it but they think they might try and sell it to someone else," he says. "I'm fine with it. The show was about the news media and conflict, war zones and cable news, and unfortunately that's going to be a timely topic for quite some time." He has some more ideas, but he's not rushing anything. "I'm hoping I will start throwing stones in the general direction of starting a new show, without really noticing it," he says. "Sometimes it's better to sneak up on yourself rather than sit down with a blank sheet of paper."

Right now, though, Moran is about to come hurtling back into view as one of the stars of Calvary, a pitch-black comedy about sex, death and religion set in rural Sligo. Written and directed by John Michael McDonagh, who previously made the backwater buddy movie The Guard, it fizzes with dirty jokes and profane sermons from an outrageous ensemble including Chris O'Dowd and Aidan Gillen. Born and raised in County Meath, Moran can relate to the kind of place where everyone seems larger than life. "In these small-town contexts, that's just how people are," he says. "There are a thousand stories about everybody, so the roles are all really heightened and defined."



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At the centre of Calvary is Brendan Gleeson's conscientious Catholic padre who, during confession, learns that a stranger plans to murder him in less than a week: a belated, misguided act of revenge for abuse at the hands of a paedophile priest. Gleeson spends what might be his last days on Earth ruefully tending to his iniquitous flock, including Moran's local lord of the manor, Michael Fitzgerald.

Fitzgerald is supposed to be despicable: a smarmy nouveau-riche fat cat who tanked the economy yet escaped without censure. He is unrepentant, crass and usually drunk, yet Moran finds something relatable, even sympathetic within this total banker. When Fitzgerald first appeared on-screen at the premiere, haughtily riding a horse, dressed in ridiculous britches, there was a cheer.

Moran plays down this response. "That's just familiarity, probably," he says. "I dunno." After the credits, he took a tentative bow with his director. "John has a great ear for dialogue," he says. "But Calvary is a very different piece of work from The Guard. It's a very unusual film, it doesn't follow prescribed lines. It's not just, 'Here's the payoff so we can all have a dance at the end.' It's more complex. It's rich and messy."

Also messy is the scene in which, in an attempt to rankle Gleeson's affable priest, Moran pulls a 16th-century artwork down from his wall – it's Holbein's The Ambassadors, the one with the anamorphic skull – then drops his trousers and threatens to pee on it. It's a shocking moment in a film not short of them. How method did Moran go? "That was not my urine, that was a bottle. Sorry to spoil it for everyone." He sips his tea: "They are my legs, though."

This fractious relationship between a priest and a banker mirrors the decline of the church in Ireland as European funding flooded into the country in the 1990s. "The church had provided spiritual riches for everybody, it was a glue for society," says Moran. "But once that started to fall apart, the gap was filled with money. It was so extreme, like capitalism 101. In the most unlikely corners of Ireland, it went from nothing to being like Dallas and then…" He mimes a mushroom cloud, "the apocalypse."

Moran watched it all happen from Edinburgh, where he has lived with his wife and young family for years, making him eligible to vote in September's referendum on independence. Eddie Izzard recently came out, Bowie-style, in favour of keeping the UK together; most Scottish comedians have a more Braveheart-ian stance. How does Moran feel about it? "Are you asking if I'm going to vote? Yes. Will I tell you how I'm going to vote? No." He thinks a "yes" vote is unlikely but is hardly surprised that it's come to this. "I've been saying it for a long time: it's the disconnect between London and the rest of the country. Why would people accept that? London is a financial citadel. They may as well put a moat around it, or attach rockets so it hovers 300ft above the rest of Britain. The idea of a trickle-down economy is horseshit."

He remains fascinated by religion, or at least that ache within us that can make faith seem attractive. "It's one of those elements of life that never goes away," he says. "People fill it with relationships, with children. Money is sometimes a short-term fix. But then they realise this vacuum is still in them and it's very powerful. There's a temptation to run away from it and to throw yourself headlong into a bath of cocaine or whatever. But it'll get you in the end. It will demand an answer from you."

Calvary is in UK cinemas on 11 Apr