The unholy trinity: The three rebel sculptors that shocked the art world with their pagan forms

If you find yourself being troubled on the doorstep by a god-botherer, try playing the pagan card. You may find it's effective in its off-putting-ness. The modern missionary is used to dealing with monotheism and atheism and versions of these things. But polytheism is trickier. Someone who seems to believe in a variety of divinities is rather hard to pin down for a conversion.

It's the same in the current god-wars. It's always mono- versus a-, and poly- never gets a hearing. And yet, practically speaking, many of us are pagans. The name may not be used, and we lack any forms of ritual. But the values by which we live suggest a world ruled by miscellaneous powers. We worship one god one minute, and another the next. We recognise how many different priorities we have and how little choice in most matters.

And if we were seeking some idols to embody our paganism, we have them too. We need look no further than a modern art gallery. For example, there are the works, made about a century ago, by three England-based sculptors: Jacob Epstein, Eric Gill, Henri Gaudier-Brzeska. Go and see them at the Royal Academy in a show called Wild Thing.

That striking phrase comes from Ezra Pound, the American poet who became impresario to the English avant-garde. He called Gaudier "a well-made young wolf or some soft-moving bright-eyed wild thing". But it also invokes the famous pop song. The show wants to emphasise how new, rebellious and outrageous their stone carving originally was.

It was. On its first appearance it was greeted with offence and protest. Physically ugly, sexually indecent, artistically mad! It's good to be reminded that these classics were once viewed with horror, and needed courage in their defence.

Still, no art can live on dead controversy. If all that you can say in favour of something is that it was once very offensive, it's not very much. Gill, Gaudier and Epstein were new once. But as Pound said in another context: "Literature is news that stays news". What in the works in Wild Thing is still new today?

Well for one thing, there's the force that's contained in their stone forms. Has anyone done it better? Gill, the homeliest of the three, puts a lovely pressure into the firm curved bodies of a calf and a pig. Gaudier's Hieratic Head of Ezra Pound is like an intersection of loaves: the geometry really strains. It also has a famous pun. From the front it shows an abstracted face. From the back it's clearly a phallus.

There's also a vein of still-surprising invention. Epstein's The Rock Drill is present both in the artist's truncated version, and the later reconstruction of its original form, showing its whole robot skeleton body and the actual rock drill it bestrides. Epstein is the great inventor. Female Figure in Flenite is an extraordinary creature. It looks like a foetus, though standing up. Then you notice that it's also pregnant. A pregnant foetus!

Behind all these effects there's an idea of what keeps things going. It's automatism. Nothing has free will. There's no inner struggle or flexibility in these bodies. They don't act. They operate as forces. And this is what allows the art to combine such incompatible elements. There's machinery and biological flourishing, instinctual activities and ritual. But all these things are somehow automatic. The world is driven.

In other words, English modernist sculpture inhabits a pagan world. It creates gods and demigods. It sees animals and plants as figures of power. It imagines strange variations on the human form. If these sculptures have something to bring us, it may be just this. If modern paganism is to get off the ground, to give itself a name, a visual identity, this is the kind of representations it needs.

A nice, odd idea. But how seriously can we take the paganism embodied in these sculptures? The marvellous Hieratic Head of Ezra Pound is clearly a god, in a sense – and like many gods he has a double aspect, wisdom and sex (not such a paradox). Likewise, The Rock Drill. It's a modern god of war and machinery, and again, like many pagan gods, he is a figure of moral ambivalence, not necessarily a positive force, but a force to be recognised.

Looking at these figures you get a funny feeling. We can't really worship these god-like sculptures, as if they had a real god behind them, but almost. They should be gods but they aren't gods. So what are they – play gods?

This is part of a longer story. Western art and Western belief have had a continual flirtation with paganism. You find statues of gods and goddesses in Renaissance gardens. You find little temples to them in 18th-century English landscape gardens. If you wonder whether the aristocrats who enjoyed these classical accountrements really believed in the theology behind them – they were officially Christians – there isn't a clear answer. Was it only a kind of high-brow game?

The work in this show is another episode in this story. But its paganism is not classical, now, it's primitivist. OK, Gill had a touch of the Roman. But with Gaudier and Epstein, it was a kind of made-up cult, loosely evoking tribal cults. It didn't of course involve any literal worship. On the other hand, it wasn't a purely artistic phenomenon. It had a strong ethical impulse.

It believed in instincts and forces. It celebrated, for instance, the basic drives of human life, and animal life too. It stood up as a counterweight to Christianity and its strict sex rules. Gill's Joie de Vivre with her open legs, his A Cocky Kid with his open legs; Epstein's sequence of fornicating doves; Gaudier's phallic imp: these images assert their values flagrantly.

And what they wanted, they got. (Other people helped.) These carvings are milestones in the history of sex, its successful liberalisation. It would be wrong to call that a religious movement, or to suggest that these sculptures were any kind of idol. It's in the nature of modern paganism to be an invisible faith. But if you'd like to have a mascot for your assumptions, the works of Gill and Gaudier and Epstein, circa 1910, can furnish you well.

Wild Thing: Epstein, Gaudier-Brzeska, Gill at Royal Academy, London W1 (020-7300 8000) 24 October to 24 January

Independent readers have a special ticket price of £7 (normally £9) for the duration of the exhibition. To redeem this offer simply quote 'Independent' at the RA ticket desk when buying tickets or by phone on 0844 209 1919