Christmas, as is widely known, is a festival that started out as pagan and was appropriated by Christians several centuries after the birth of the man they regard as their saviour. But these days, however much John Sentamu may object, for most people, certainly in this country, Christmas is just a nice time at the end of the year when we wind down for a few days, celebrate the end of one year, the beginning of another, meet up with family and friends and have a good time. It's Christian connotations are irrelevant.
A friend of mine, from a Hindu background, is coming back to the UK for Christmas. But he's not coming back for a mass for Christ, he's coming back to see family and friends and have a good time. Christmas is just a shorthand for a time when we get together and are a bit nicer to each other than usual. The religious aspect has become a sideshow. That is not the doing of we illiberal atheists, it is just reality. Get over it.