Justice/Fancy, Academy, Oxford

Gallic glam in a head-to-head with a pair of swinging Christians – and the support act wins

'But I thought they were male-fronted!" she says when we walk through the door. "Er, they are," I tell her. As Bowie once sang, it's confusing these days. Indeed, Jessie Chaton, singer with French glam-trash rockers Fancy, might have stepped out of the lyrics to "Rebel Rebel", except that it isn't just your mother who's in a whirl, not sure if he's a boy or a girl.

It must be stated, right away, that Fancy, the support act for fellow French duo Justice, aren't for everyone. Anybody who had a problem with the Darkness, for starters, should look away now, the rest should read on with relish, because Fancy are the most entertaining rock'*'roll band I've seen in a long time.

Chaton is a skinny beanpole with an unfeasibly enormous afro (the phrase "le nouveau Marc Bolan" has been used), a knee-length boa, obscenely tight spandex pants with one leg silver and the other leg black, wild boggling eyes, apache stripes on his cheeks, lipsticked mouth and – this, in context, is brilliant – a five o'clock shadow. I'd call him a Nancy boy, but it turns out he's from Paris.

He is, however, a screaming queen. Literally. Chaton's voice conveys a helium hysteria we haven't heard since The Sweet's Steve Priest didn't have a clue what to do. He sings, and talks, in the highest-pitched voice known to man. (Boy, does he talk! Chaton is the cockiest frontman this side of the Hives' Howlin' Pelle Almqvist.) If it's an act – and the guy next to me asks "Is that voice for real?" – then it's an act he keeps up throughout.

The motley crew (a grizzled rocker on drums, an indie pretty boy on guitar, and a black androgyne, about whose precise gender we're still arguing in the taxi home, on bass) that forms his band looks like the Angry Inch, and sounds like Suzi Quatro.

Tracks such as "Inside of You" and "King of the World" are driven by Chinnichap/RAK beats and bold, brassy riffs that shake their booties like a dockside prozzie. During a berserk cover of the Pointer Sisters' "I'm So Excited", Chaton performs a partial striptease, and sticks one hand inside his knickers like an X-rated Jacko. When he squeals the line "I want to love you, squeeze you, throw my arms around you ...", his limbs look long enough to enact that promise with the entire front row. Fancy will either get under your skin or under your skirt. One way or another, Le Glam is gonna get you.

Usurped, that's what Justice's review has been. But these things happen. Especially when you're essentially just another couple of blokes headbanging earnestly for an hour behind a console.

Justice, whose name any The Day Today fan can't help but hear in the reanimated voice of Louis Armstrong or Martin Sheen, are the French electro-house duo of Xavier de Rosnay and Gaspard Augé, signed to Ed Banger records (whose fem-rap heroine Uffie's disembodied vocals are thrown into the mix at various points tonight) and best known for their collaboration with Simian on the mighty (if now overplayed) dancefloor anthem "We Are Your Friends", and their own equally anthemic "D.A.N.C.E.".

They're also, it must be said, swinging Christians. By all accounts they're nice chaps who don't proselytise in person, but on stage, their religion couldn't be any more in your face: their sole prop is a huge, illuminated cross, of the kind you see atop tacky roadside spires in the southern United States (and in the cringeworthy closing scenes of The Notorious Bettie Page). One thinks of those trendy vicars you used to read about circa 1991, trying to turn their naves into raves to capture the youth vote. Suddenly, "Waters of Nazareth" becomes inseparable in the mind from "Rivers of Babylon", except that Boney M never got an Erol Alkan remix.

As someone who's halfway through The God Delusion, and punching the air and cheering at the end of every page, it feels like an affront to see Justice shoving their anti-intellectual mumbo-jumbo in our faces (literally) in this of all cities, Dawkins' stomping ground. Never mind the Grammys or the Brits: these guys are going for the Templeton Prize.

Not that Rosnay and Augé don't have their finger on the pop pulse. "D.A.N.C.E.", with its uplifting children's chorus, mixes seamlessly and enjoyably in and out of a set of Daft Punkish Franco-house where every eighth bar is filtered as if it's coming from the room next door.

But, guys – even if it's only a few 100-watt bulbs in a box – spare me the sermon.