Classical Theodora Glyndebourne

"The Jews will not come to it because it is a Christian story, and the ladies will not come, because it is a virtuous one" (Handel on Theodora, 1750). Time was when nobody would come because it was a Peter Sellars production. Times change. Sellars' powerful new staging of Handel's penultimate oratorio could seriously damage your prejudices. It will certainly confound the reactionaries. Because it simply isn't possible to say of this show "wonderful performance, pity about the production". The two are truly, madly, deeply inseparable. They meld in mysterious ways.

Forget AD304 and all that, this is here and now - history and human nature recycled. George Tsypin's set is essentially a gallery, towering relics of Roman glassware set against crisp white walls. Very chic. "Civilised." People we recognise as contemporaries casually drift in. Private view, lecture, press conference? Whatever. Suddenly, it's a media circus. And just as the attendant music is at its most exquisite (a solo oboe in rapt ascent), we glimpse our first armed guard. Enter the Roman President, all cosmetic smiles and handshakes. Today's publicity stunt is a feigned heart-attack. The President goes down spouting hardline enforcement policy as the paramedics apply CPR. But he's up and smiling again before you can register the full horror of his statement.

So far, so very Sellars. But you don't have to be Sophocles to follow his thinking. Ancient or modern, the so-called "civilised", "free" world is historically nothing of the sort. Indeed, you could argue that the social activist in Sellars tips the scales too much in favour of goody Christians over baddy pagans (Handel himself is much more even-handed). The evening's only serious miscalculation is a vulgar drunk scene in which President Valens is very much the leader of lager louts.

Still, it's as viable a context as any for Handel's oratorio of principle and morality, and besides, the real impact of Sellars' staging lies in his profound sympathy - his oneness - with Handel's score, and how best to express in physical terms what was, after all, conceived as purely vocal. Hand gesture, with its roots in Baroque practice, is once again his chosen language, and with a chorus of real "individuals", well schooled in every gesture, he has fashioned a powerful corporate metaphor for Christianity as a democracy for truth, love, compassion, humanity. What's more, we can actually see Handel's part-writing in action as specific gestures pull focus on the vocal counterpoint.

For the principals, it's as if feeling is being taken from the body and offered with the voice. Low lighting magnifies it in silhouettes cast on the walls. In the case of Lorraine Hunt's magnificent Irene, the generosity of spirit and voice needs no magnification. Every aria is right up there with the finest Handel singing I have ever heard in the theatre. Likewise David Daniels, a sensational American counter-tenor, whose entirely natural and wide-ranging timbre is worlds away from the hooty, artificial falsettos we have come to expect. Dawn Upshaw's heartfelt Theodora must be careful not to push the emotion outside the discipline of the vocal line, but she is never less than real, and the quality of ecstasy never deserts her singing.

She and Daniels deliver their final duet in numbing pianissimo, every ornament in perfect symmetry, the serenity, the humanity of the music disturbingly counterpointed with the grotesque and inhuman spectacle of them strapped to gurneys and tilted up like crucifixes. Execution by lethal injection, the "civilised" world's answer to crucifixes: barbaric but clean. Here, as throughout, William Christie and the Orchestra of the Age of Enlightenment gave this wonderful music - the most transcendental in all Handel (one achingly introspective number after another) all the room in the world - with key cadences placed in such a way as to make it feel, in every sense, eternal.

n To 21 June (01273 813813)