There are two holidays in the Western world, both of them falling on December 25th and both of them now called Christmas. There's the Christian festival, the Feast of the Nativity - the one with the creche and Baby Jesus and sacred songs; and there's the other one, the secular Yule - the holiday with the tree and the presents and Santa Claus, the holiday Irving Berlin wrote secular songs for. The holiday with holly and turkey and trimmings, the one with snow and tinsel and old fashioned Father Christmases, the lights and ornaments and reindeer... Most people in this country may keep them both, but precious few keep only The Nativity. Many more than that keep Yule...
There is certainly a religious component to Christmas - but which religion? Christmas as it is practiced in the US at least, and I expect around the European-origin world at large, isn't really about Baby Jesus® anymore.
So I celebrate - and say "Merry Christmas".
And now, to all my readers:
Whatever you want those words to mean.
Rejoice with the return of the Sun and the lengthening of days. Be well, be happy, be kind to one another. This is our life: live it well together.