Preacher man: The Art of William Holman

He was the father of the Pre-Raphaelites, a man who strived to inspire virtue. But 250 years on, the religious art of William Holman Hunt fails to convert Tom Lubbock

The Light of the World: once there was a print in every home. In a dark wood, a cuddly Christ, holding an elaborate lantern, stands and glows and knocks at an overgrown door. The beard may look a little false, and the metaphor may be mixed – asking to be let in, and lighting the way – but this was the image of Jesus that the 19th century gave to the world. As the world could once have told you, it was the work of William Holman Hunt.

"I painted the picture with what I thought, unworthy though I was, to be by Divine command." Hunt's motivations were always the highest. He painted The Light three times – twice in the early 1850s at the start of his long career, a final time at its end in the early 1900s. All three versions are showing together in Holman Hunt and the Pre-Raphaelite Vision at Manchester Art Gallery. It gets a bit more glowy, a bit more commanding, but it doesn't change much. Why should it?

It's the image that speaks for Hunt's whole work. Look across the pictures gathered in this survey, and you find an artist whose priorities are evangelical. Unlike other Victorians, he isn't after creating beauty, observing nature, inventing stories, dramatising dilemmas. He's sending a spiritual or ethical call to the viewer's soul: pay attention, change your life. "All art," said Hunt, "is a branch of that spirit of appeal from the Divine to man, which has been working ever since our kind knew the difference between good and evil."

His images have remained proverbial – The Awakening Conscience, where a fallen woman suddenly sees the light in her seducer's arms; The Shadow of Death, in which the young Christ yawns and stretches and casts his "crucified" shadow on the wall of the carpenter's shop; The Scapegoat, a sacrificial animal, cast out into the purple Palestinian desert. And the fact that these works and others have stayed around, the kind of pictures a cartoonist could quote and expect to be recognised, is a tribute. But with this artist, fame can never be enough. Facing his work today, we shouldn't duck its original challenge. Can his call still reach us? Holman Hunt, our contemporary?

Not likely. With Hunt, we simply can't compete. In terms of communication, his art leaves us standing, gaping. The last version of The Light went on a tour of the British Empire on which it was seen by seven million people. At the interment of the artist's ashes at St Paul's, thousands of the public turned up to pay him honour. You could buy memorial cards showing "The Hand of Holman Hunt" – a photo of the artist's right hand holding a pencil, like the precious body-part of a saint, unmistakeably a relic. Now try and think of a living artist. No art speaks or matters to us like Hunt's once spoke and mattered.

The thing we can't compete with is more than an individual talent. It's a cultural moment. Holman Hunt lived at a time when art was taken more seriously, by more people, than at any time before or since – a time when a creative type might become a sage, a prophet, a quasi-saint. Holman Hunt, self-taught painter, founder member of the pre-Raphaelites, through the strength of his own seriousness, seized this moment.

He gave art a guiding role in life. "The eternal test of good art is the influence it is calculated to have on the world... What the people are led to admire, that they will infallibly become." Back moral and religious truth with visual force! And the most impressive sign of his earnestness was that, after his first success, Hunt set off on a series of punishing visits to the Middle East so that the stories of Jesus could be painted where they first happened, and their reality communicated to the modern viewer.

There seems to me no point in trying to turn Hunt into an artist we can like. What's valuable about him is just how resistant, how alien, his art and his ideas of art are. Other Pre-Raphs can be enjoyed on something like our own terms – we find them surreal, excessive, clever, spooky, perverse, inadvertently funny. Hunt: no. He can't be recovered in this way. He's not surreal. He's not clever. He's not funny. He's frankly oppressive.

He oppresses on three fronts. Symbolism. Moralism. Materiality. In a Hunt painting, every detail signifies something. It preaches a lesson. And – most oppressively – it has a solid, glistening physical presence. These three forms of "heaviness" work together, so that the insistent meaningfulness of the scene is stressed again by the stiff, swollen, shiny substance of each body and each object. It's an unrelenting emphasis. Hunt can't trust his viewers to notice anything. They must be shown it all, have it pointed out at every point, in case they miss the lesson.

This is an art that's giving us visible models of vice and virtue, temptation and innocence, sin and duty, to draw us on the right way. "In the exercise of her high function Art must sort out the good and beautiful from the base and hideous." But the problem with this function is not just that it's out of fashion. It's hard to see how, in Hunt's hands, it functions at all. His art doesn't sort anything out. His all-over emphasis backfires. His stolid and inflexible way of picturing makes him peculiarly incapable of conveying a vivid sense of differences. Everything – animal, vegetable, mineral – ends up looking stuck and impotent in its fixed material existence. It's a preserved, crystallised world (as in fruit), in which good and evil become imperceptible.

Of course, if you know the story, if you know who Jesus is, or the seducer, or the bad shepherd, or the wicked woman, or the innocent, you can factor that knowledge in – and read it up, of course. But given his high purposes, it's striking how hard it is to detect his moral direction when you don't already know. The woman having a good time in Il Dolce Far Niente: would that be a good kind of good time, or a bad kind? I'm sure it's one or the other, but which I've no idea.

Even The Scapegoat, stranded in its hellish desert, might leave you thinking that this creature was actually one of the damned, rather than a sacrifice symbolising the crucified Christ. And don't tell me these images are interestingly ambiguous. They're not. They're simply inert. Or actually counteractive. The Triumph of the Innocents must be the most repellent celebration of infancy in the history of art.

Hunt's art comes down to us as a puzzle. It was an art that desired to speak to its audience with authority and eloquence on matters of supreme importance, and did so triumphantly. But for us it has become almost inarticulate. This isn't because our values have changed – that barrier can be imagined over. It's because its visual language, so clogged by its own insistent imperative to get its points across, has no power to stir us one way or another – except sometimes in the opposite way it wants us to go.

But I must not say that Hunt has no surprises. One image in this show hits you in the face, one from his early trips to the Middle East. The Great Pyramid is an extraordinary vision, the evacuation of the kind of meaningfulness Hunt usually pursues. It's the sphinx, and seen from the back. A featureless, unrecognisable blob. A solid nothing. The blank of the world.

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Holman Hunt and the Pre-Raphaelite Vision, Manchester Art Gallery (0161 235 8888), to 11 January