If certain traditional features of Christmas in radio-land seem to have vanished from the schedules – the apparent absence of anything about the Beatles is almost unprecedented – then other ancient standbys continue to be wheeled out from their flyblown storage rooms into the merciless festive light. Wonderful as it is to come across a series in which serious people talk seriously about the things they believe, I never look at the roster for Belief, whose annual sit-down begins on 23 December (BBC Radio 3), without ­experiencing a faint sense of déjà vu.It is not that this year’s guests – the former Chief Justice Lord Woolf, the comic actress Sally Phillips, the writers Elif Shafak and Ian McEwan, the theologian and historian Diarmaid MacCulloch a