MUSIC; Christian Composer, Inspired by Allah's 99 Names

By MICHAEL WHITE

FOR anyone in Britain and for millions of television viewers elsewhere, a defining image of the year 1997 was the aerial view of the coffin of Diana, Princess of Wales, inching through the darkness of Westminster Abbey. And the defining soundtrack to that image was a stark lament sung by the abbey choir that captured the moment with heart-stopping potency.

Overnight the worldwide exposure of ''Song for Athene'' transformed John Tavener from a distinguished classical composer into a public figure. New fans registered his odd appearance: tall and thin, with long hair parted in the middle and the '60s-pop-star look of shirts unbuttoned to the navel. He was re-evaluated. He was knighted. And for many he became almost a spiritual guide: All his work was steeped in Christianity. Or, as he liked to say, ''primordial tradition.''