This is a more common question than you might expect in the English speaking church, historically.

Andy, Darren, and Josh discuss some of the biblical and historical reasons a Christian should celebrate Christmas

Augustine - Why Celebrate Christmas? (Abridged sermon 185 - https://www.crossroadsinitiative.com/media/articles/why-celebrate-christmas/)

Augustine unabridged sermon 185 and other Christmas sermons (https://books.google.co.uk/books?id=r3fYAAAAMAAJ&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false)