MUSIC / Prankster or prophet?: Nicholas Williams on the BBC's four-day Tavener retrospective

Inscribe the name of God and set his image opposite,' said Leonardo da Vinci, affirming the power of religious painting, 'and you will see which is the more revered.' John Tavener feels much the same about music. Fifty this year, he's been celebrated in a four-day BBC festival, Ikons, showing how 1960s standard- bearer has come close to being Orthodox saint and missionary.

Which of the Taveners you prefer depends very much on how you like your sermons. As Ikons showed, he's been preaching much the same message about death and resurrection since his first successes. But, like all good preachers, he's rung the changes on his text. Earlier scores are wicked, ironic and multilayered, a surprise for listeners familiar only with the literal truths of The Protecting Veil.

Either way, he has surprising ways of touching the heart - and often in miniature. Two brief 'In memoriams', Responsorium and Song for Athene, given by the BBC Singers at St Giles on Saturday afternoon, drew warm, spontaneous applause from a packed house moved by the immediacy of their grieving. This was recent, Byzantine Tavener, formal and archaic, as in Thunder Entered Her beginning the programme. By contrast, there was still a whiff of Anglican pathos in the sweet harmonies of The Lamb, despite the hard-headed thoughts behind Blake's words.

More of that, admittedly distorted, could be heard in the Celtic Requiem at the Barbican that evening. Not just for Sixties connoisseurs (the Beatles paid for the 1969 recording), this was a valid music-theatre experience on the subject of mortality. The New London Children's Choir, in rhymes, riddles and the 'Song of Jenny Jones', ably supported a glittering cast. Earlier, there was more of Tavener the miniaturist in the Sixteen Haiku of Seferis, given committed readings by soprano Patricia Rozario and tenor Thomas Randle, and Tavener the ritualist in Palintropos, played by pianist Rolf Hind and a BBC Symphony Orchestra of sounding gongs, celesta and brass.

Where the break between prankster and prophet occurs is difficult to locate. Ultimos Ritos of 1972, concluding the festival on Monday in the candlelit splendour of Westminster Cathedral, explored St John of the Cross's dark night of the soul - with Tavener's own music 'put to sleep' by the Crucifixus of Bach's B minor Mass. The 1968 In Alium, revived in the same concert, with strings, keyboards, ring modulator and tape conducted by Richard Hickox, showed the composer firmly as joker.

Perhaps the point of change, or of ideal balance between the two, occurs in the Akhmatova Requiem (1980), given a taut, charged account on Sunday night with Penelope Walmsley-Clark in the testing soprano role and Stephen Richardson, bass, intoning the Russian liturgy. There's Shostakovich in the background, but the celesta colouring in one early number, and the sombre presence of bells, are entirely Tavener's own.

Nothing could be further removed in sound than The Protecting Veil, played by Steven Isserlis with Rozhdestvensky conducting. Admiration tends to divide here - between those who find untapped possibilities in those first, incandescent minutes, and those who can follow the eight continuous sections as a convincing whole. Tavener's recent large-scale music, the Akathist of Thanksgiving at Westminster Abbey on Friday for example, is like the paradise it aspires to: unblemished by ambiguity. A genuine ikon offers nothing less, of course. But to what extent art can exist when faith substitutes for meaningful contradiction only the individual can decide.