"Therefore my dear brothers, stand firm. Let nothing move you. Always give yourselves fully to the work of the Lord, because you know that your labor in the Lord is not in vain"
1 Corinthians 15:58
Just think, if Christmas didn't really happen, if God didn't really become human, if Christmas is just some kind of nice story, then the joy of Christmas, all the partying and celebrating is only temporary but the suffering of this world is permanent.
But if Christmas really happened, and God really became a human being at Christmas, and He broke into this world to redeem us, then the suffering of this world is only temporary and the joy of the new heavens and the new earth and the city of the living God along with all the angels who rejoice is permanent!