Biblical proportions

Handel's Messiah has long been a staple for choral societies. In 1784, Westminster Abbey staged a series of concerts marking the 25th anniversary of the composer's death. A monumental Messiah was the centrepiece, boasting no fewer than 500 performers and an audience of 4,500. It's everywhere at this time of year, a wonderful "sing" for amateurs and professionals alike. Great for audiences, too - although at more than two and a half hours, the piece can be demanding. To stop it sagging, you have to concentrate on telling the story rather than ornamenting the music.

Messiah has become synonymous with Christmas, although Charles Jennens's libretto, which adroitly stitches together biblical texts, spans Christ's birth, death and resurrection. In fact, the real drama of the work lies in the second half, which tells the Easter story. Yet the work is performed less frequently in the UK at Easter - and almost never in the US. There, it really is a Christmas fixture, performed three or four times by almost every orchestra in every state between Thanksgiving and Christmas.

There is a danger of Messiah turning into a seasonal warhorse - something you do by rote, the concert-going equivalent of attending midnight mass. The piece deserves better than that. I have conducted Messiah more than 150 times and always find something new and unexpected in it; it changes according to venue, audience, mood and singers. I adapt to my soloists, just as Handel would have done. Although it's a well-known work, can I ever say I fully understand what it is capable of? No. As with all great art, you never quite have its measure.

I'll know it's time to stop conducting Messiah when my back no longer tingles with excitement when I get to the Amen chorus, an electrifying moment. The beauty and flexibility of the music, serving so dramatic a narrative, makes for a compelling evening, as long as the piece is performed with urgency. Many people sit through Messiah as therapy, but that underplays the quality of the score: ignore the traditions that have built up around it, strip it down to its essentials, rediscover Handelian rhythms - and a peerless piece of art emerges.

One thing that makes it special for me is that, right from the first performance in Dublin in 1742 (where it was played "for relief of the Prisoners in the several Gaols, and for the Support of Mercer's Hospital in Stephen's Street and of the Charitable infirmary on the Inns Quay"), the work has been a fundraiser. From 1750 until his death in 1759, Handel performed it annually for Thomas Coram's Foundling Hospital in London; he bequeathed a score to the hospital to enable it to carry on the tradition.

In Europe, Messiah is performed less regularly than in the UK and US. Germany and the Netherlands like to programme Bach's Passions at Easter, and it is really only in Spain that we are beginning to see a plethora of Messiahs, mostly performed by UK-based ensembles. I will be in Madrid and Pamplona with my ensemble, the Sixteen, just before Christmas, and there will be "community Messiahs" all over Spain.

These are a sort of Messiah X Factor. In the spring, thousands of would-be singers are auditioned. Around 400 are chosen, mostly young, and they rehearse devotedly until performances in December, when a professional orchestra and choir join them. The results are staggering, and the performances - as I found when I conducted them - very rewarding. Handel, a great innovator and entrepreneur, would have loved the idea.

Strangely, I didn't really know Messiah when I was young because, as a family, we didn't go to concerts. I was a chorister at Canterbury cathedral and sang the occasional chorus, but it wasn't until I was at Oxford that I sang part one of Messiah. It was only as a rather indifferent professional tenor that I sang it complete for the first time, at Westminster Abbey.

My relative ignorance was helpful when I came to conduct: I had no preconceived notions of how it should be. When I first did it in 1985, I wanted to go back to exactly what Handel wrote. I had become aware of a tendency, even in so-called period performances, to dwell on style and lose the sense of the whole. Tradition had imposed bad habits: in the past, people had felt there were things in the score that were not clear and had tried to iron them out, but in doing so they had flattened it, lost the vital Handelian rhythms. Stripping away the layers imposed by traditional performance liberated the work from this straitjacket, making it come alive.

Messiah represents Handel's direct, personal response to the Bible, but the pacing remains essentially operatic. He was always an opera man, anxious to tell his story dramatically. The overture brilliantly sets the mood for the rest of the parts, filling us with a sense of hope and lightness. Then Handel launches into the sublime Comfort Ye, which calms everyone down. It's Handel saying: "I'm going to make you listen, because this is a long story." He takes you into another world and has this ability to uplift people, then calm them, before taking them up again. As a result, Messiah never fails.

· Harry Christophers is founder and conductor of vocal ensemble and orchestra the Sixteen.