Directed by Kevin Smith. Starring Michael Parks, Melissa Leo, John Goodman, Michael Angarano 18 cert, gen release, 98 min

KEVIN SMITH is a good thing. An amiable guy with a lot to say about the ailments afflicting contemporary America, the director radiates common sense and blimpish humanity. It’s such a shame that his films aren’t very good.

To be fair, Red State, an evisceration of Christian extremism, is Smith's most coherent work in half a decade. Framed as a horror film, it is fired up by righteous anger and powered along by grisly momentum. Yes, it's repetitive, over- written and dragged down by too much sermonising (both literal and figurative). But, after monstrosities such as Jersey Girland Cop Out,we must savour what humble pleasures Smith can rustle up.

Red Statebegins with an archetypal group of young layabouts – transatlantic Inbetweeners– reading an online ad inviting young men to participate in group sex with a middle-aged lady. They pile into their van and head for the outskirts of town. But it's all a ruse. The deranged matriarch (Melissa Leo, back in hillbilly gear) to a clan of wildly right-wing Christian fundamentalists has placed the ad as part of a plan to lure "fags" to their death. Before too long, one of our heroes finds himself bound to a cross in the clan's meeting hall.

Some readers will detect allusions to the infamous Westboro Baptist Church. Nervous of lawsuits (or, perhaps, damnation), Smith makes sure to insert a line acknowledging the existence of that clan in another place.

This clumsy piece of shoehorning is characteristic of a film that never whispers when it can bellow. Though uncharacteristically skilfully edited, Red Statefeatures Smith's usual clumsily explicit dialogue and painfully extended monologues.

The Old Testament language feels more contrived than, well, the Old Testament. A final paranoid musing on the war on terror could have been lifted straight from the maddest corner of the internet.

And yet. Despite having only one idea in its head (if that), Red Statedoes compel the sensitive viewer to question Smith's apparent decision to retire from film-making. There's a singular voice in here. He just needs somebody to turn the volume down a tad.