Worried about the grotesque gap between rich and poor? Concerned about the excesses of consumer society? Then the V&A's new exhibition, Baroque 1620-1800: Style in the Age of Magnificence, should give you an almighty reality check. Conspicuous consumption? The most bonusswollen banker has nothing on your average 17th or 18th-century monarch. Let me introduce you to King John V.

The Portuguese king decided that he wanted a royal chapel. He bought the best Roman artists imperial money and autocracy could buy, got them to fit it out, had it blessed by the Pope, then shipped it in its entirety to Lisbon. Step through the door of the chapel of St John the Baptist in São Roque and the eyes are assaulted by gold and jewels. Everywhere. Every inch. Incredibly, King John used up most of his country's New World fortune on this one exercise in excess. Partly reassembled at the V&A are its encrusted chalices, cruets, bells, censers, crosses and candlesticks, tapestries and costumes woven almost solid with gold thread, and everything with as many knobs, bells and whistles as space will allow. Stand in front of it and you are bathed, as King John intended, in the light of Heaven.

This is an utterly inappropriate time - or a grotesquely prescient one - for a blockbuster show on Baroque, the latest in the V&A's exemplary series recreating the world view behind global styles. Never have so many golden curlicues, tassles and twiddles been assembled in one place. That is part of the problem. British eyes have been tutored by puritanism towards the plain and the practical. What do we do when confronted by an objet made from a gold and jewel-studded ostrich egg, complete with porcelain neck and legs? Two hours here is like gorging on Black Forest gateau and Wall's Viennetta, followed by tiramisu, rum baba and a side order of trifle.

The Baroque seems alien to our north European norms. It's a Latin thing, something for hotter climes, more passionate people. Of course, like other puritans such as the Swedes and Germans, even we had our Baroque moment in the late 17th century, but our high points - such as James Gibbs's church of St Mary-le-Strand, rendered here in an intricate model - are positively minimalist compared with São Roque or Versailles. And, while the Baroque dominated southern Europe for nearly two centuries, Britain could only take a few decades of it before needing a good lie down with the smelling salts.

The exhibition at first inevitably overwhelms. But its curator, Michael Snodin, retains a firm grip. His first thesis is Baroque as “the first world style,” he explains. “It had its origins in Italy, Spain, France and Portugal, but it spread around the world.” He points out an elaborately carved, wooden-fronted house. “French Baroque. Built in the remote countryside in Norway. Norway!” How's that for globalisation and stylistic fusion?

Baroque is a geopolitical story, the style of European empire and expansion. This is what happens when the keys to the goody store of the entire planet are given to autocratic European leaders. They raid the coffers of Latin American gold and silver mines, and pillage the lacquer of Japan and the porcelain of China. You find French silversmiths in Sweden and Chinese carvers in Indonesia making objets for the rich of Portugal. The result is either glorious eclecticism or a dog's dinner. Baroque is inherently impure, mongrel. “And each place it spread to had its own reasons for adopting it,” Snodin says. In Britain its arrival coincided with the restoration of the monarchy after 1660. “Popish” Baroque was not quite Oliver Cromwell's cup of tea. Instead, it became associated with the return of Charles II and the “natural” order of things, with the reopening of theatres and pubs - with fun. And though it never quite lost its “taint” of Roman Catholicism, it seemed bound up with the return of old-fashioned British individualism and licentiousness. It was the plain style of Cromwell that seemed most associated with “alien”, centralised dictatorship.

For much of Europe, though, the opposite held true. The second central thesis of this exhibition is that Baroque, at heart, was one big PR campaign - with the Vatican as its pumping heart, its missionaries, cardinals and Jesuits the veins and nerves - to re-establish the order of things after the shock of the Reformation. It also had to cope with new threats, such as the rise of Enlightenment rationalism and science and Turks at the gates of Vienna. It was the Renaissance world order - God at the centre - rebranded with extra lashings of gold to attract and sate the masses.

Before mass literacy, three-dimensional style was the method of communication. We think of ourselves as living in a world of overwhelming sensory stimulation. Baroque is where it all began. Every steeple, every painting, every statue, every little scrap of visual and three-dimensional communication was employed by those with a vested interest in maintaining the status quo. In our secular age, we're blind to it. Walk through a city such as Rome or Lisbon nowadays and those saints on church walls, those putti on candelabras or those scenes in a Caravaggio painting are just sightseeing. But in the 17th century they were alive. People walked through a material world of propaganda. This presents a problem for the exhibition. Most of the glories of Baroque art, such as the Hall of Mirrors at Versailles, or Francesco Borromini's church of San Carlo alle Quattro Fontane in Rome are three-dimensional set pieces. The V&A has to rely on what can be transported. But the exhibition's scenographic design and the fascinating objects selected cleverly conjure up the artifice and drama of the Baroque world view.

The room exploring the rise of theatre, opera and performance is particularly telling. Theatres were built in every major city; European powers outdid one another with the magnificence of their productions, in which even details such as an Italian bassoon are “dramatised” (as a sea dragon). High Mass becomes “a compelling, multisensory perfomance”. In towns, holy or royal processions hammer home the “natural order” by parading it in front of your eyes. The show opens with a painting of the Carousel for Queen Christina of Sweden in the courtyard of the Palazzo Barberini in Rome in 1656, an elaborate confection of sky-high headdresses and fire-breathing dragons.

Drama extended to the immobile, too. Baroque paintings become snapshots of action: in Rubens' The Descent from the Cross (1611) here, protagonists are caught mid-flow, and the weight of Jesus is palpable. In architecture, walls weren't composed with the harmony of the Renaissance: they curled and writhed; columns multiplied, twisted and collided, like Borromini's intricate design here for the baldacchino - the bronze canopy - at St Peter's. To the passing congregation, the gesturing saints on church walls were almost flesh. Gian Lorenzo Bernini reconfigured Rome into one giant Baroque performance piece, with town planning for civic rituals, and “total works of art” such as St Peter's, explored here, where everything right down to the chalices on the altar is employed to get across his “concetto” - the total impact a place might have on the emotions.

St Peter's was literally Heaven on Earth, Heaven made substance, God materialised into gold leaf. Even the pincer-like colonnade at its entrance was literally and figuratively the vice-like embrace of the Church. Just as in High Mass you consume the body and blood of Christ, so in Baroque style, gold, rubies and excess were like sunbeams issuing from the very heart of God, a little taste of what was to come if you were good.

Rome, and God, were at the apex of the Baroque world, but Paris and Louis XIV weren't far behind. The final rooms of the exhibition are devoted to the secular world. Or the semi-secular. For just as the Vatican was as much a worldly empire as a religious one, so the whole authority of Baroque Europe's secular autocrats depended on them maintaining the illusion that they were God's representatives on Earth. Indeed it was regarded as almost subversive for an aristocrat not to flaunt his or her wealth, not to consume conspicuously.

The exhibition is at its best exploring this semi-political, semi-religious order in its literal and symbolic manifestation - the palace - where the sequence of spaces was employed to make the monarch as magnificent as airbrushed modern celebrities, and to reaffirm the social order. The palace to end all palaces, Versailles, set the standard: its Hall of Mirrors (1684) was designed to make the Sun King dazzle that bit more, while the closer you were allowed to the royal body denoted your status.

Again, the physicality of the material world is key. Closer to the dressing room, closer to the skin of the monarch, the closer you were to truth. Just look at the copy of Hyacinthe Rigaud's 1701 portrait of an old Louis XIV here, his actual body invisible beneath the weight of robes and cloaks. Beneath the pomp lay the dangerous modern truth - science, decay, everyone basically the same. An afternoon in these halls and you understand the French Revolution just that little bit better.

Baroque: Style in the Age of Magnificence, V&A, (020-7942 2000, www.vam.ac.uk), from Saturday to June 19

Pearls of the Baroque

Figure of a camel made from gold and pearls

With its golden base topped by a camel of encrusted pearls, far left, this hideous 18th-century figure explains the name Baroque - from the Portuguese pérola barroca, misshapen pearl.

Design for part of a column for the canopy in St Peter's Basilica, Rome

This intricate design by great Baroque architect Francesco Borromini has columns twisting like barley sugars, wreathed in blossoming creepers buzzing with bees - the inert material world comes alive.

Rhinoceros horn beaker

Exotic new materials from empires were almost magically endowed with qualities and allusions - rhino horn as an aphrodisiac. Don't miss the erotic scene on the base.

Model of the head of St Teresa Bernini's Ecstasy of St Teresa (1647-52) captures the Heaven-meets-Earth intensity of the religious experience in the saint's near orgasmic features.

Time and Death

This extraordinary wax tableau of man from life to death is gruesome with its decaying corpse fed upon by rats. Baroque could be macabre as well as ecstatic.

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