Whether people 'buy into' it or not it is Christmas that we are celebrating. It is Christmas day.
If people don't believe in Jesus or God or Christianity or Santa Claus or Father Christmas or even the Pagan side of things they still (in Britain at least) generally speaking take the day off work. Also people of other faiths do actually (again in Britain at least) celebrate Christmas day as do atheists.
What are the police playing at?
Is it all a part of the slow creeping destruction by stealth from within of particularly Christianity and of traditional Britain?